âčïž Skipped - page is already crawled
| Filter | Status | Condition | Details |
|---|---|---|---|
| HTTP status | PASS | download_http_code = 200 | HTTP 200 |
| Age cutoff | PASS | download_stamp > now() - 6 MONTH | 1.2 months ago |
| History drop | PASS | isNull(history_drop_reason) | No drop reason |
| Spam/ban | PASS | fh_dont_index != 1 AND ml_spam_score = 0 | ml_spam_score=0 |
| Canonical | PASS | meta_canonical IS NULL OR = '' OR = src_unparsed | Not set |
| Property | Value |
|---|---|
| URL | https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html |
| Last Crawled | 2026-03-09 01:11:38 (1 month ago) |
| First Indexed | 2020-04-24 23:43:51 (5 years ago) |
| HTTP Status Code | 200 |
| Meta Title | Coronavirus Antibody Tests: Can You Trust the Results? - The New York Times |
| Meta Description | A team of scientists worked around the clock to evaluate 14 antibody tests. A few worked as advertised. Most did not. |
| Meta Canonical | null |
| Boilerpipe Text | Advertisement
SKIP ADVERTISEMENT
A team of scientists worked around the clock to evaluate 14 antibody tests. A few worked as advertised. Most did not.
From left, Dr. Caryn Bern, Dr. Alexander Marson, Patrick Hsu and Dr. Jeffrey Whitman, who have helped lead an effort to assess antibody tests for the coronavirus.
Credit...
Anastasiia Sapon for The New York Times
Published April 24, 2020
Updated Aug. 19, 2020
The researchers worked around the clock, in shifts of three to five hours, hoping to stave off weariness and keep their minds sharp for the delicate task.
They set up lines of laboratory volunteers: medical residents, postdoctoral students, even experienced veterans of science, each handling a specific task. They checked and rechecked their data, as if the world were depending on it. Because in some ways, it is.
For the past few weeks, more than 50 scientists have been working diligently to do something that the Food and Drug Administration mostly has not: Verifying that 14
coronavirus antibody tests
now on the market actually deliver accurate results.
These tests are crucial to reopening the economy, but public health experts have raised urgent concerns about their quality. The new research, completed just days ago and posted online Friday, confirmed some of those fears: Of the 14 tests, only three
delivered consistently reliable results
. Even the best had some flaws.
The research has not been peer-reviewed and is subject to revision. But the results are already raising difficult questions about the course of the epidemic.
Surveys of residents in the Bay Area, Los Angeles and New York this week found that substantial percentages tested positive for antibodies to SARS-CoV-2, the official name of the new
coronavirus
. In New York City, the figure was said to be as high as 21 percent. Elsewhere, it was closer to 3 percent.
The idea that many residents in some parts of the country have already been exposed to the virus has wide implications. At the least, the finding could greatly complicate plans to reopen the economy.
Already Americans are scrambling to take
antibody
tests to see if they might escape lockdowns. Public health experts are wondering if those with positive results might be allowed to return to work.
But these tactics mean nothing if the
test
results canât be trusted.
In the new research, researchers found that only one of the tests never delivered a so-called false positive â that is, it never mistakenly signaled antibodies in people who did not have them.
Two other tests did not deliver false-positive results 99 percent of the time.
But the converse was not true. Even these three tests detected antibodies in infected people only 90 percent of the time, at best.
The false-positive metric is particularly important. The result may lead people to believe themselves immune to the virus when they are not, and to put themselves in danger by abandoning social distancing and other protective measures.
It is also the result on which scientists are most divided.
âThere are multiple tests that look reasonable and promising,â said Dr. Alexander Marson, an immunologist at the University of California, San Francisco, and one of the projectâs leaders. âThatâs some reason for optimism.â
Dr. Marson is also an investigator in the Chan Zuckerberg Biohub, which partly funded the study.
Other scientists were less sanguine than Dr. Marson. Four of the tests produced false-positive rates ranging from 11 percent to 16 percent; many of the rest hovered around 5 percent.
âThose numbers are just unacceptable,â said Scott Hensley, a microbiologist at the University of Pennsylvania. âThe tone of the paper is, âLook how good the tests are.â But I look at these data, and I donât really see that.â
The proportion of people in the United States who have been exposed to the coronavirus is likely to be 5 percent or less, Dr. Hensley said. âIf your kit has a 3 percent false-positive, how do you interpret that? Itâs basically impossible,â he said. âIf your kit has 14 percent false positive, itâs useless.â
Dr. Hensley said the study nonetheless was well designed and the results pressing, given the sudden proliferation of antibody tests on the market and the push to use them to lift lockdowns.
âI think this is exactly the kind of study that we need right now,â he said.
Dr. Marson and his colleagues said they were drawn to the study for that very reason.
As universities in the Bay Area shut down all research not related to the coronavirus, some researchers began focusing on ways to improve diagnostic tests for SARS-CoV-2.
Dr. Marson and his collaborator, Patrick Hsu, a bioengineer at the University of California, Berkeley, anticipated that antibody tests would also face questions about quality.
In mid-March, Dr. Hsu heard that a friend, a venture capitalist who owns a network of 1,000 community clinics in the New York area, had ordered thousands of rapid antibody tests. Investors and entrepreneurs seemed to be distributing them around San Francisco, too.
âI realized, âGosh this is really the Wild West,ââ Dr. Hsu said. âWe needed to figure out which of these would really work.â
The duo recruited Dr. Jeffrey Whitman and Dr. Caryn Bern, who last year published an
analysis of antibody tests
for Chagas disease. Other graduate students and postdoctoral fellows volunteered to help perform the evaluations.
The team began with a modified version of the method Dr. Whitman had devised to validate Chagas tests. The researchers created a biosafety-certified space, obtained the needed approvals and procured hundreds of blood samples from two Bay Area hospitals.
They also purchased tests from Chinese manufacturers, clearing customs regulations and sometimes accepting Uber deliveries in the middle of the night.
In all, the investigators analyzed 10 rapid tests that deliver a yes-no signal for antibodies, and two tests using a lab technique known as Elisa that indicate the amount of antibodies present and are generally considered to be more reliable.
Image
Tori Yamamoto, left, and Ujjwal Rathore, who worked with Elisa antibody tests. The photo was taken with a phone in a sterile container.
Credit...
Joe Hiatt/University of California, San Francisco
Listen to âThe Dailyâ: The State of Testing
Rigorous testing has been key to reopening economies in Asia. So why is the U.S. lagging behind in administering tests?
transcript
bars
0:00/26:29
-26:29
transcript
Listen to âThe Dailyâ: The State of Testing
Hosted by Michael Barbaro, produced by Rachel Quester and Jessica Cheung, and edited by M.J. Davis Lin
Rigorous testing has been key to reopening economies in Asia. So why is the U.S. lagging behind in administering tests?
archived recording (gov. andrew cuomo)
Everybody wants to reopen.
So how do you actually do that intelligently? Well, you have to test.
[music]
michael barbaro
From The New York Times, Iâm Michael Barbaro. This is âThe Daily.â Today, as governors across the country debate when and how to reopen their economies â
archived recording 1
We are nowhere near where we need to be with testing supplies.
archived recording 2
Yeah, look, weâre nowhere near where we need to be on testing. Letâs just be straight with folks.
archived recording 3
You know, our testing is increasing, but itâs not increasing nearly fast enough.
michael barbaro
â they say that the single biggest impediment is their inability to measure and monitor infection rates in their communities.
archived recording 1
Weâve been fighting for testing.
archived recording 2
We need to be doing robust testing in order to really assess when and how itâs safe to resume life.
michael barbaro
Katie Thomas on the state of testing. Itâs Tuesday, April 28.
Katie, when state officials talk about testing as a decisive factor in whether and when to reopen their economies, what do they mean?
katie thomas
Well, for the governors, this is really an essential tool. Itâs what they are going to need to rely on if theyâre going to reopen their economy and their communities. I mean, think of it like a fire department that doesnât have an essential tool like hoses. They canât put out fires. And the governors, if they canât have consistent and widespread testing throughout their states, then, you know, they canât see when a new hot spot is popping up or infections are rising, and whether theyâre successfully beating the virus or not.
michael barbaro
And exactly what kind of testing are we talking about here?
katie thomas
Well, thereâs two kinds of tests. The first one is the one that many of us have been talking about for a while, the diagnostic testing, which actually tests for pieces of the actual virus, and that will tell you and your doctors whether you are actively infected with the virus and whether you have it. Then the second group of testing, which is really kind of just getting underway right now, is called antibody testing. Thatâs the idea that after you have had the virus and youâve recovered, your body has developed antibodies, which help fight off the virus. Generally â we donât know for sure, science still doesnât know, but people are pretty much operating on the assumption that if you have these antibodies in your system, then you are immune, at least for now, from getting infected again from this coronavirus.
michael barbaro
Gotcha. So one of these tests says, youâve got the virus. The other says, youâve had the virus. Letâs start with the diagnostic test, right, because that is the test that people talk to us about when they talk about flattening the curve and limiting the spread. So where do things stand with that test?
katie thomas
So as you probably remember, things got off to a pretty bad start in the U.S. with diagnostic testing back in January. The C.D.C., whose job it is to initially get things rolling with developing a test and then sending it out to all the public health labs around the country so that they can start testing, encountered basically a manufacturing problem as they were scaling up the tests and mailing them out. As they mailed out that first batch to the public health labs around the country and the labs started testing them to make sure that they were correct, they quickly realized that they had a problem. And what happened is some contamination got into the tests that basically made it so that they revealed an invalid result, and so they couldnât be relied upon.
michael barbaro
Mm-hmm.
katie thomas
So this set back testing in the country significantly and for weeks, because basically those public health labs then couldnât do the testing that they had planned on doing, and almost all of the testing in the country for the month of February was only done through the C.D.C. lab.
michael barbaro
Right, creating a huge bottleneck at a crucial moment when the virus is spreading all over the country.
katie thomas
Exactly. And while the C.D.C. was scrambling to fix the problem, this whole other system of private labs, university and hospital labs that were ready and who wanted to develop their own tests, they were slowed down, they said, by the Food and Drug Administration, which they felt wasnât moving quickly enough to allow them to develop their own tests. And so not only did you have the C.D.C. suddenly unable to disperse its tests to public health labs around the country, you also almost had this backup system that also couldnât get going initially. And so that was basically the story for the whole month of February, is that the state public health labs couldnât do their testing and neither could the hospitals and the academic medical centers that also wanted to get in the game and start testing.
michael barbaro
So catch us up from that original sin in the diagnostic testing in the U.S. At this point, how much diagnostic testing is underway in the U.S., and how does that compare to where everybody wants it to be?
katie thomas
Yeah. So things have picked up significantly since then. I mean, the whole month of March, finally, the F.D.A. â you know, they did make a policy change that allowed all of these labs to start developing and doing their own tests. Another thing that happened in the month of March is that these big testing companies that make these huge, high-capacity testing machines that enable labs to do thousands of coronavirus tests a day, they also completed their work on their tests and started selling them. And so there was a very big ramp up in the capacity for these labs to start doing the tests. But then, you know, as these labs started doing all these tests, they started to run into new problems.
michael barbaro
Like what?
katie thomas
Well, we started to see shortages of all kinds of different things. All of the supplies that you need in order to do these tests, suddenly they came under strain. The best example is probably the swabs that you need to conduct a test. Itâs this very long, skinny swab that almost looks like a Q-Tip, but itâs a very specialized swab that you stick all the way back into your nose to where your nose meets your throat. And those swabs are in demand globally because, obviously, this isnât just happening in the U.S. This is happening around the world.
michael barbaro
Of course.
katie thomas
One of the biggest companies that makes these swabs is actually an Italian company that is based in northern Italy, and thatâs where their factory is, as well.
michael barbaro
And of course, northern Italy is where there was a giant outbreak of the virus.
katie thomas
Thatâs right. So yeah, so in addition to the swabs, everything else started going into short supply, as well. There were the chemical reagents that are needed to do the tests. Thereâs the liquid that you insert the swab in to transport it to the lab. That started becoming short. Containers, the little vials that you stick the swab into, those started to become short. And then in addition, the shortage of masks and other personal protective equipment that weâve all heard about with hospitals and medical providers, the person whoâs doing the test also needs to have that protective wear, and so those shortages also started to affect the number of tests that providers could do. You know, if they didnât have masks, then they couldnât do a test, and if they didnât have enough swabs, then they couldnât do a test.
michael barbaro
Hm. So it turns out thereâs this kind of, like, unseen chain of items required to do testing, and even if you have plenty of tests you canât do the tests without each and every one of them.
katie thomas
Thatâs right.
michael barbaro
So at this point, how many diagnostic tests are being done in the U.S.?
katie thomas
Well, the number is likely going up, and the last couple of days itâs gone up significantly. You know, no one knows for sure exactly how many tests are being done, but the best estimates are that, you know, in the last several days, the U.S. has been doing about 250,000 tests a day.
michael barbaro
Now, Katie, is that a lot or a little, given that we are a nation of nearly 300 million people?
katie thomas
It sounds like a lot of tests, but actually, experts say that weâll have to do many times that in order to really reopen the country. Some say we may need to be doing a million or more in order to really know what weâre dealing with and to get a handle on the virus.
michael barbaro
Now, we keep hearing at the federal level that the U.S. has enough diagnostic tests, right? The Trump administration says at these daily news briefings, capacity has grown significantly, there is sufficient testing. So how does that square with what youâre describing?
katie thomas
Right. And thatâs the issue is that thereâs a big disconnect right now between the labs and what they theoretically could do in a day if they were sent X amount of tests, and the number of tests that hospitals that are actually testing the patients can do in a single day, given these ongoing shortages of everything from swabs to masks to the vials to send the swabs in.
michael barbaro
So the White House is accurate when it says, a lot more testing is possible. The only problem is that possible is not the same as having everything you need to do all the tests.
katie thomas
Thatâs right.
michael barbaro
So just to summarize where things are: When it comes to diagnostic tests of the coronavirus â this essential frontline weapon in telling governors and public health officials how many people have the virus â- once this major bottleneck at the C.D.C. got solved, then testing has really expanded, in part because the private sector was allowed to get involved. But thereâs still a major problem with the supply chain that basically means there isnât nearly as much testing done as everybody wants there to be done and thinks there needs to be done.
katie thomas
Thatâs right. Weâve come very far from where we were, and the picture is changing by the day. Weâre still not anywhere close to where most people feel like we need to be in order to really reopen the country.
[music]
And itâs right in the midst of that, of still ramping up these diagnostic tests, that weâre now kind of shifting our attention and focus toward this other big category of tests, which is the antibody test.
michael barbaro
The test that tells you if youâve already had the virus?
katie thomas
The test of whether youâve had the virus. Thatâs correct.
michael barbaro
And how, Katie, is that test going?
katie thomas
Well, that is proving to be just as complicated and problematic maybe as the diagnostic tests were.
michael barbaro
Weâll be right back.
Katie, what do we need to know about this second test, the antibody test?
katie thomas
Yeah. Well, we really need this new category of tests, the antibody tests, as we move forward and communities think about reopening, and thatâs for a number of reasons. One is just to get a feel for how far has the virus spread in your community. How many people have gotten it? Unlike the diagnostic tests which are kind of a moment in time, the antibody test tells you, have you ever had it, which is a valuable and slightly different piece of information. The other piece of this is, if we can accurately identify who has had it and who hasnât, it might help us figure out which health care workers can safely go back to work, and who can kind of rejoin our community.
michael barbaro
Right. And of course, which parts of the economy can reopen. We talked to our colleague Donald McNeil about this. This is the test that would help us distinguish the immune from the still susceptible, and the immune, if this test works, they become a very privileged class of people who get to do almost everything.
katie thomas
Right. I mean, theoretically, thatâs the idea.
michael barbaro
And so where are we in the development of that test?
katie thomas
So the F.D.A. and the federal government took a completely different approach when it came to the antibody tests. The F.D.A. came under criticism for having been too slow to allow the development of the diagnostic tests, and so when it came to the antibody tests, they almost overcorrected and they went in the other direction. And they went to all of the testing companies and basically said, if you want to develop an antibody test, go ahead, go for it. And rather than coming to us for approval before you can sell it, we are going to let you develop the tests, do your own validating, make sure that you are comfortable that your test works, and then once you are comfortable that it works, you can start selling the test. You donât need approval from us. And so, you know, the F.D.A. has said that theyâre now aware of dozens of companies that are selling or developing these antibody tests, and itâs really become almost like a wild, wild west of testing.
michael barbaro
So after having kind of held up the private sector when it came to the diagnostic test, this time they are supercharging the private sector on the antibody test, and putting a huge amount of trust in these corporations to do this and do it right.
katie thomas
Yes. Thatâs right.
michael barbaro
And so how has it gone?
katie thomas
Itâs been a really mixed bag. Thereâs just a huge variety of tests that are out there, and a huge variety of accuracy. In fact, there was a study that just came out by independent researchers that took a look at 14 of these tests, and it found that out of those 14 tests that they examined, only three delivered consistently reliable results.
michael barbaro
Wow. Three of 14 tests that are on the market already?
katie thomas
Thatâs right. Yeah. And some of the tests, a group of the tests, produced whatâs known as a false positive rate up to 16 percent of the time.
michael barbaro
And explain that. What does a false positive mean when it comes to an antibody test for the coronavirus?
katie thomas
Sure. So a false positive would be when the test incorrectly identifies somebody as having had the antibodies for the coronavirus when they didnât really have it â when they had never had the virus.
michael barbaro
And a 16 percent false positive rate â correct me if Iâm wrong â that sounds really bad for a test.
katie thomas
Yeah. I mean, it means that if you have 100 people, 16 of those people could be incorrectly identified as having had the virus and having antibodies to the virus.
michael barbaro
And that, of course, would be quite dangerous, because a false positive for the antibodies is basically the false understanding that you may be immune to the virus and would act accordingly â go out into the world, return to work, maybe not wear a mask.
katie thomas
Thatâs right. Thatâs right. It also would mean that, you know, if youâre the mayor or the governor or, you know, a public health leader, you also just donât have a very good picture of whatâs going on in your community and how many people have had the virus. And that could really be bad in a community where there arenât a lot of people that truly have the virus, because it could lead that community to think that theyâre at a different stage in this outbreak than they truly are, and it could lead them to make decisions about how to reopen and how to move forward in a way that really doesnât accurately reflect what the risks truly are.
michael barbaro
Right. Iâm thinking about places in rural America, for example, where if suddenly an antibody test were given to everyone in that community and infection rates were really low, in reality, a high false positive rate test might make everyone think, Oh, wow, weâve come out the other side of this epidemic and a lot of us are O.K., when in fact the virus just hasnât really washed over that community yet.
katie thomas
Thatâs right, when in fact itâs really an issue about the accuracy of the test versus the reality on the ground.
michael barbaro
Hm. So this government plan to avoid the problems of the diagnostic test rollout by taking a really hands-off approach and relying on private companies, that doesnât seem to have worked out very well. In fact, it seems, to a certain degree, to have backfired.
katie thomas
It has. I mean, you know, if you are a governor or a public health official in a community, you now have the job of trying to figure out which test you want to use and try and learn for yourself kind of whether it works or not.
michael barbaro
Are any of the tests highly reliable? Do any of the tests have very low false positive rates?
katie thomas
Yes. There are some tests that experts said are good and are accurate, and some of the really big testing companies â Abbott is one example â have recently come out with their own antibody test, and the feeling is that these tests are measurably better than some of the other ones that have come on the market.
michael barbaro
But it feels like overall, just to establish exactly where we are at this moment when it comes to testing, there are still significant problems with diagnostic tests because of those supply chain issues you talked about earlier, and we donât have anywhere near as reliable a set of antibody tests as everybody thinks we need.
katie thomas
Thatâs right. I mean, we basically havenât mastered either one of these tests.
michael barbaro
Katie, is testing just really hard in a public health emergency like the coronavirus, or do we just keep screwing this up kind of uniquely in the U.S.? Because now we have two examples â the diagnostic and the antibody test â where we canât quite seem to get it right when we very much need to get it right.
katie thomas
Yeah. I think some of this goes to the bigger picture of where we are at as a country with our health care system. Even before the pandemic, and even more so now that we are in a pandemic, the truth is is that our health care system is a huge jumble. Thereâs the federal government, thereâs all of the states, there are for-profit hospitals, there are nonprofit hospitals. Thereâs people who are covered by Medicare, by Medicaid, by insurance through their employer. Itâs all a big mix, and some would say a big mess, and this is all playing into testing, and who is testing, and which company do we use, and how do we get our supplies. So just to give you an example, say youâre a patient and youâre in the hospital and your doctor wants to give you a coronavirus test. They open up their computer and thereâs an electronic system that they use, and when they hit click to order a test, that test order will go out to the company that they happen to have a relationship with, say itâs LabCorp. Now, if LabCorp, at that moment of the crisis, has a week-long backlog, itâs not so easy for that hospital to quickly pivot to a different lab that might have capacity. So, you know, itâs very hard, for example, for that doctor, then, to get on the phone and maybe call 10 other labs in the area to check and see how quickly that they can process their test. And I can give you an example on the other side of that equation, which is, I know of a lab director who has all of that excess capacity. He could be processing hundreds more tests a day than he is, and yet heâs not getting calls from hospitals for their tests.
michael barbaro
Hmm. Youâre describing a situation in which the lack of any kind of centralized system in U.S. health care is really hampering our ability to test.
katie thomas
Right. I mean, in a pandemic, you really need to be able to move quickly and decisively, and, you know, I think weâve long known that our health care system is very fragmented, but weâre really seeing that play out in the example of testing. Whether itâs the supply chain issues, or getting antibody testing out there and accurate, itâs showing all of the kind of little ways that this system that we have is not quite up to the task and is slowing us down.
[music]
michael barbaro
Right. And the price of that is that it will take much longer for governors around the country and for local health officials to really get a grasp on where the virus is and to reopen our economy.
katie thomas
I think, unfortunately, thatâs right.
michael barbaro
Katie, thank you very much.
katie thomas
Thanks for having me.
michael barbaro
On Monday, the White House released new national guidelines on testing that put much of the burden on states rather than the federal government. Testing, the plan said, would be state-managed and locally executed. The federal government, the guidelines said, would be a, quote, âsupplier of last resort.â
Weâll be right back.
Hereâs what else you need to know today. On Monday, the U.S. Centers for Disease Control and Prevention named six new symptoms of the coronavirus in a move that reflects the unpredictable ways that the virus can affect individual patients. Previously, the C.D.C. listed just three symptoms â fever, cough, and shortness of breath. It has now included chills, repeated shaking with chills, muscle pain, headache, sore throat, and loss of taste or smell. And New York State has canceled its presidential primary, saying that with Bernie Sanders out of the race, the June 23 election would be purely symbolic and would detract from the stateâs response to the pandemic. Supporters of Sanders, whose name would have remained on the New York ballot, had pushed for the primary to be held, hoping to win more delegates that would give them greater influence over the partyâs platform at the Democratic National Convention.
Thatâs it for âThe Daily.â Iâm Michael Barbaro. See you tomorrow.
Listen
· 26:29 min
Suited up in protective gear, the team worked in shifts of three to five hours in a sort of socially distanced factory line.
One researcher spotted the test with a blood sample, and another added the necessary chemical solutions; then two independent readers looked at the test, and a last person recorded the results. Still other team members analyzed the results, sometimes working through the night.
In the early hours of recent mornings, they handed the baton to Dr. Tyler Miller and his colleagues at Massachusetts General Hospital, who were conducting a slightly different analysis of three tests, including one evaluated in San Francisco.
The Bay Area team finished evaluating 12 tests in record time, less than a month. By comparison, the Chagas project required a team of three people working for more than a year just to compare four tests.
Having a study design already in hand helped speed the work, but there was one key difference. Decades of data have shown that Chagas disease elicits lifelong immunity. For this study, the team had no idea how quickly SARS-CoV-2 antibodies might turn up in the blood, or at what levels.
[
Like the Science Times page on Facebook.
| Sign up for the
Science Times newsletter.
]
New tests also usually compete with an established gold standard. Lacking such a standard, the team instead compared all the tests in a âhead-to-head bake-off to see whoâs the winner,â Dr. Hsu said.
Each test was evaluated with the same set of blood samples: from 80 people known to be infected with the coronavirus, at different points after infection; 108 samples donated before the pandemic; and 52 samples from people who were positive for other viral infections but had tested negative for SARS-CoV-2.
Tests made by Sure Biotech and Wondfo Biotech, along with an in-house Elisa test, produced the fewest false positives.
A test made by Bioperfectus detected antibodies in 100 percent of the infected samples, but only after three weeks of infection. None of the tests did better than 80 percent until that time period, which was longer than expected, Dr. Hsu said.
The lesson is that the tests are less likely to produce false negatives the longer ago the initial infection occurred, he said.
The tests were particularly variable when looking for a transient antibody that comes up soon after infection, called IgM, and more consistent in identifying a subsequent antibody, called IgG, that may signal longer-term immunity.
âYou can see that antibody levels rise at different points for every patient,â Dr. Hsu said. The tests performed best when the researchers assessed both types of antibodies together. None of the tests could say whether the presence of these antibodies means a person is protected from reinfection, however.
The results overall are promising, Dr. Marson added. âThere are multiple tests that have specificities greater than 95 percent.â
Rapid antibody tests are generally used to get a simple yes-no result, but the team assigned the positive results â which appear as bands on a test strip â a score from zero to six. They trained readers to interpret those results, and found their decisions often agreed and were supported by the more quantitative Elisa tests.
âIf you train the readers well, they can start to be reliable,â Dr. Marson said of rapid tests. âThat is critical to understand if these tests could ever be deployed.â
The team at Mass General set a higher bar for specificity; they considered a score of one for the intensity of a band to be a negative result, rather than a score of zero.
Perhaps because they eliminated the fainter bands â the ones most likely to be erroneous â their estimate of specificity for BioMedomics, the one test that was evaluated by both teams, was more than 99 percent, compared with the San Francisco teamâs estimate of 87 percent.
Other experts were skeptical of the scoring approach, however. âThatâs not really a method that would give you a real quantitation,â said Florian Krammer of the Icahn School of Medicine at Mount Sinai in New York.
Dr. Krammer has developed a two-step Elisa test that he said has 100 percent specificity and delivers a measure of the quantity of IgM and IgG antibodies a person has. Scoring a rapid testâs bands might offer some data for a scientific study, he said, âbut I would not make any decisions based on that.â
Dr. Krammer said false positives are less of an issue for assessing how widely the virus has spread in the population. If a test has a known false-positive rate, scientists can factor that into their calculations, he said.
But false positives become dangerous when making policy and personal decisions about who can go back to work. âYou donât want anybody back to work who has a false positive â thatâs the last thing you want to do,â Dr. Krammer said.
Scanwell Health, a Los Angeles-based start-up, has ordered millions of test kits from Innovita, a Chinese manufacturer, and has applied to the Food and Drug Administration to market the tests for at-home use.
In the new study, the Innovita test detected antibodies in 83 percent of infected people and yielded a false-positive rate of 4 percent.
Dr. Jack Jeng, chief medical officer of Scanwell Health, said the study looked at an earlier version of Innovitaâs test and not the ânewer, improved versionâ his company had ordered. âIt will be interesting to see how it performs,â he said.
Dr. Marson and his colleagues have acquired tests from nearly 100 manufacturers, and plan to continue comparing them. The scientists also hope to expand their sample set to include people who were mildly ill or did not feel ill at all, and to stratify their data by age and the presence of chronic conditions.
âThis is just the beginning,â Dr. Marson said. âOur goal would be to keep going till we feel thereâs adequate supply in the market.â
Apoorva Mandavilli
is a reporter focusing on science and global health. She is the 2019 winner of the Victor Cohn Prize for Excellence in Medical Science Reporting.
A version of this article appears in print on
April 26, 2020
, Section A, Page 6 of the New York edition with the headline: False Positives: 11 of 14 Antibody Tests Are Unreliable, Researchers Find
.
Order Reprints
|
Todayâs Paper
|
Subscribe
Related Content
The Covid-19 Pandemic
Callaghan O'Hare for The New York Times
Eric Lee/The New York Times
Tierney L. Cross/The New York Times
More in Health
Hesslefors/ullstein bild, via Getty Images
Federica Bordoni
Kristian Thacker for The New York Times
Kent J. Edwards for The New York Times
Editorsâ Picks
Warrick Page/HBO Max
Illustration by Tomi Um
Trending in The Times
John McConnico for The New York Times
Don Hogan Charles/The New York Times
Illustration by Sam Whitney/The New York Times
An Chen
Lindsey Whitaker
Philip Cheung for The New York Times
Matteo Prandoni/BFA.com
Artu Nepomuceno
Devin Oktar Yalkin for The New York Times
Advertisement
SKIP ADVERTISEMENT |
| Markdown | [Skip to content](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#site-content)[Skip to site index](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#site-index)
Search & Section Navigation
Section Navigation
Search
[Health](https://www.nytimes.com/section/health)
[Log in](https://myaccount.nytimes.com/auth/login?response_type=cookie&client_id=vi&redirect_uri=https%3A%2F%2Fwww.nytimes.com%2Fsubscription%2Fonboarding-offer%3FcampaignId%3D7JFJX%26EXIT_URI%3Dhttps%253A%252F%252Fwww.nytimes.com%252F2020%252F04%252F24%252Fhealth%252Fcoronavirus-antibody-tests.html&asset=masthead)
Sunday, March 8, 2026
[Todayâs Paper](https://www.nytimes.com/section/todayspaper)
[Health](https://www.nytimes.com/section/health)\|Coronavirus Antibody Tests: Can You Trust the Results?
https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html
- Share full article
Advertisement
[SKIP ADVERTISEMENT](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#after-top)
Supported by
[SKIP ADVERTISEMENT](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#after-sponsor)
# Coronavirus Antibody Tests: Can You Trust the Results?
A team of scientists worked around the clock to evaluate 14 antibody tests. A few worked as advertised. Most did not.
- Share full article
From left, Dr. Caryn Bern, Dr. Alexander Marson, Patrick Hsu and Dr. Jeffrey Whitman, who have helped lead an effort to assess antibody tests for the coronavirus.Credit...Anastasiia Sapon for The New York Times
[](https://www.nytimes.com/by/apoorva-mandavilli)
By [Apoorva Mandavilli](https://www.nytimes.com/by/apoorva-mandavilli)
Published April 24, 2020Updated Aug. 19, 2020
The researchers worked around the clock, in shifts of three to five hours, hoping to stave off weariness and keep their minds sharp for the delicate task.
They set up lines of laboratory volunteers: medical residents, postdoctoral students, even experienced veterans of science, each handling a specific task. They checked and rechecked their data, as if the world were depending on it. Because in some ways, it is.
For the past few weeks, more than 50 scientists have been working diligently to do something that the Food and Drug Administration mostly has not: Verifying that 14 [coronavirus antibody tests](https://www.nytimes.com/2020/08/19/nyregion/new-york-city-antibody-test.html) now on the market actually deliver accurate results.
These tests are crucial to reopening the economy, but public health experts have raised urgent concerns about their quality. The new research, completed just days ago and posted online Friday, confirmed some of those fears: Of the 14 tests, only three [delivered consistently reliable results](https://covidtestingproject.org/). Even the best had some flaws.
The research has not been peer-reviewed and is subject to revision. But the results are already raising difficult questions about the course of the epidemic.
Surveys of residents in the Bay Area, Los Angeles and New York this week found that substantial percentages tested positive for antibodies to SARS-CoV-2, the official name of the new [coronavirus](https://www.nytimes.com/2021/03/26/health/coronavirus-covid-testing.html). In New York City, the figure was said to be as high as 21 percent. Elsewhere, it was closer to 3 percent.
The idea that many residents in some parts of the country have already been exposed to the virus has wide implications. At the least, the finding could greatly complicate plans to reopen the economy.
Already Americans are scrambling to take [antibody](https://www.nytimes.com/2020/06/18/health/coronavirus-antibodies.html) tests to see if they might escape lockdowns. Public health experts are wondering if those with positive results might be allowed to return to work.
But these tactics mean nothing if the [test](https://www.nytimes.com/2020/05/05/health/crispr-coronavirus-covid-test.html) results canât be trusted.
In the new research, researchers found that only one of the tests never delivered a so-called false positive â that is, it never mistakenly signaled antibodies in people who did not have them.
## Editorsâ Picks
[I Make Connections. Hereâs What Iâm Actually Thinking.](https://www.nytimes.com/2026/03/07/insider/nyt-connections-game-writer-wyna-liu.html)
[A Vexing Problem for College Students: Course Availability](https://www.nytimes.com/2026/03/06/your-money/college-students-course-availability.html)
[Bobby Cannavale Loves âHeated Rivalryâ and His Bearded Dragon](https://www.nytimes.com/2026/03/07/arts/television/bobby-cannavale-bearded-dragon-scarpetta.html)
Advertisement
[SKIP ADVERTISEMENT](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#after-pp_edpick)
Two other tests did not deliver false-positive results 99 percent of the time.
But the converse was not true. Even these three tests detected antibodies in infected people only 90 percent of the time, at best.
The false-positive metric is particularly important. The result may lead people to believe themselves immune to the virus when they are not, and to put themselves in danger by abandoning social distancing and other protective measures.
It is also the result on which scientists are most divided.
âThere are multiple tests that look reasonable and promising,â said Dr. Alexander Marson, an immunologist at the University of California, San Francisco, and one of the projectâs leaders. âThatâs some reason for optimism.â
[Trumpâs Remarks Prompt Warnings on Disinfectants](https://www.nytimes.com/2020/04/24/us/coronavirus-us-usa-updates.html)
Dr. Marson is also an investigator in the Chan Zuckerberg Biohub, which partly funded the study.
Other scientists were less sanguine than Dr. Marson. Four of the tests produced false-positive rates ranging from 11 percent to 16 percent; many of the rest hovered around 5 percent.
âThose numbers are just unacceptable,â said Scott Hensley, a microbiologist at the University of Pennsylvania. âThe tone of the paper is, âLook how good the tests are.â But I look at these data, and I donât really see that.â
## More on the Virus
- **Is It Cold, Flu or Covid?:** With similar symptoms, it can be difficult to tell which illness is which. [Hereâs what to know](https://www.nytimes.com/2025/11/25/well/cold-flu-covid-symptoms.html).
- **Heart Problems:** One study found that a Covid infection [doubled the risk of a major cardiovascular event for up to three years afterward](https://www.nytimes.com/2024/11/22/well/covid-heart-health.html). And the risk of a heart attack [triples within the first few weeks](https://www.nytimes.com/2025/10/29/well/viral-infections-covid-flu-heart-attacks.html) after an infection, another suggested.
- **Long Covid in Children:** People under 21 [are](https://www.nytimes.com/2025/09/30/health/long-covid-children.html) [twice as likely to develop long-term health consequences](https://www.nytimes.com/2025/09/30/health/long-covid-children.html) after a second coronavirus infection, a large study found.
- **Covid Shots****:** The F.D.A. [approved updated Covid vaccines](https://www.nytimes.com/2025/08/27/health/fda-covid-vaccines-rfk-jr.html) and limited who can get the shots. Children [under 12 need different versions of the vaccines](https://www.nytimes.com/2025/10/07/well/covid-vaccine-children-parents-issues-rfk-jr.html), but many pharmacies and pediatriciansâ offices arenât stocking them. [Here's what to know](https://www.nytimes.com/2025/08/27/well/covid-vaccines-guidelines-fall-2025.html).
- **Gut Issues:** Why does Covid cause [diarrhea, constipation, pain and bloating? Here are some suggestions for](https://www.nytimes.com/2024/12/12/well/eat/covid-symptoms-diarrhea-constipation-pain-bloating.html) what to do about these conditions.
The proportion of people in the United States who have been exposed to the coronavirus is likely to be 5 percent or less, Dr. Hensley said. âIf your kit has a 3 percent false-positive, how do you interpret that? Itâs basically impossible,â he said. âIf your kit has 14 percent false positive, itâs useless.â
Dr. Hensley said the study nonetheless was well designed and the results pressing, given the sudden proliferation of antibody tests on the market and the push to use them to lift lockdowns.
âI think this is exactly the kind of study that we need right now,â he said.
Dr. Marson and his colleagues said they were drawn to the study for that very reason.
As universities in the Bay Area shut down all research not related to the coronavirus, some researchers began focusing on ways to improve diagnostic tests for SARS-CoV-2.
Dr. Marson and his collaborator, Patrick Hsu, a bioengineer at the University of California, Berkeley, anticipated that antibody tests would also face questions about quality.
In mid-March, Dr. Hsu heard that a friend, a venture capitalist who owns a network of 1,000 community clinics in the New York area, had ordered thousands of rapid antibody tests. Investors and entrepreneurs seemed to be distributing them around San Francisco, too.
âI realized, âGosh this is really the Wild West,ââ Dr. Hsu said. âWe needed to figure out which of these would really work.â
The duo recruited Dr. Jeffrey Whitman and Dr. Caryn Bern, who last year published an [analysis of antibody tests](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6879282/) for Chagas disease. Other graduate students and postdoctoral fellows volunteered to help perform the evaluations.
The team began with a modified version of the method Dr. Whitman had devised to validate Chagas tests. The researchers created a biosafety-certified space, obtained the needed approvals and procured hundreds of blood samples from two Bay Area hospitals.
They also purchased tests from Chinese manufacturers, clearing customs regulations and sometimes accepting Uber deliveries in the middle of the night.
In all, the investigators analyzed 10 rapid tests that deliver a yes-no signal for antibodies, and two tests using a lab technique known as Elisa that indicate the amount of antibodies present and are generally considered to be more reliable.
Image
Tori Yamamoto, left, and Ujjwal Rathore, who worked with Elisa antibody tests. The photo was taken with a phone in a sterile container.Credit...Joe Hiatt/University of California, San Francisco
### Listen to âThe Dailyâ: The State of Testing
Rigorous testing has been key to reopening economies in Asia. So why is the U.S. lagging behind in administering tests?
transcript
Back to The Daily
0:00/26:29
\-26:29
transcript
## Listen to âThe Dailyâ: The State of Testing
### Hosted by Michael Barbaro, produced by Rachel Quester and Jessica Cheung, and edited by M.J. Davis Lin
#### Rigorous testing has been key to reopening economies in Asia. So why is the U.S. lagging behind in administering tests?
archived recording (gov. andrew cuomo)
Everybody wants to reopen.
So how do you actually do that intelligently? Well, you have to test.
\[music\]
michael barbaro
From The New York Times, Iâm Michael Barbaro. This is âThe Daily.â Today, as governors across the country debate when and how to reopen their economies â
archived recording 1
We are nowhere near where we need to be with testing supplies.
archived recording 2
Yeah, look, weâre nowhere near where we need to be on testing. Letâs just be straight with folks.
archived recording 3
You know, our testing is increasing, but itâs not increasing nearly fast enough.
michael barbaro
â they say that the single biggest impediment is their inability to measure and monitor infection rates in their communities.
archived recording 1
Weâve been fighting for testing.
archived recording 2
We need to be doing robust testing in order to really assess when and how itâs safe to resume life.
michael barbaro
Katie Thomas on the state of testing. Itâs Tuesday, April 28.
Katie, when state officials talk about testing as a decisive factor in whether and when to reopen their economies, what do they mean?
katie thomas
Well, for the governors, this is really an essential tool. Itâs what they are going to need to rely on if theyâre going to reopen their economy and their communities. I mean, think of it like a fire department that doesnât have an essential tool like hoses. They canât put out fires. And the governors, if they canât have consistent and widespread testing throughout their states, then, you know, they canât see when a new hot spot is popping up or infections are rising, and whether theyâre successfully beating the virus or not.
michael barbaro
And exactly what kind of testing are we talking about here?
katie thomas
Well, thereâs two kinds of tests. The first one is the one that many of us have been talking about for a while, the diagnostic testing, which actually tests for pieces of the actual virus, and that will tell you and your doctors whether you are actively infected with the virus and whether you have it. Then the second group of testing, which is really kind of just getting underway right now, is called antibody testing. Thatâs the idea that after you have had the virus and youâve recovered, your body has developed antibodies, which help fight off the virus. Generally â we donât know for sure, science still doesnât know, but people are pretty much operating on the assumption that if you have these antibodies in your system, then you are immune, at least for now, from getting infected again from this coronavirus.
michael barbaro
Gotcha. So one of these tests says, youâve got the virus. The other says, youâve had the virus. Letâs start with the diagnostic test, right, because that is the test that people talk to us about when they talk about flattening the curve and limiting the spread. So where do things stand with that test?
katie thomas
So as you probably remember, things got off to a pretty bad start in the U.S. with diagnostic testing back in January. The C.D.C., whose job it is to initially get things rolling with developing a test and then sending it out to all the public health labs around the country so that they can start testing, encountered basically a manufacturing problem as they were scaling up the tests and mailing them out. As they mailed out that first batch to the public health labs around the country and the labs started testing them to make sure that they were correct, they quickly realized that they had a problem. And what happened is some contamination got into the tests that basically made it so that they revealed an invalid result, and so they couldnât be relied upon.
michael barbaro
Mm-hmm.
katie thomas
So this set back testing in the country significantly and for weeks, because basically those public health labs then couldnât do the testing that they had planned on doing, and almost all of the testing in the country for the month of February was only done through the C.D.C. lab.
michael barbaro
Right, creating a huge bottleneck at a crucial moment when the virus is spreading all over the country.
katie thomas
Exactly. And while the C.D.C. was scrambling to fix the problem, this whole other system of private labs, university and hospital labs that were ready and who wanted to develop their own tests, they were slowed down, they said, by the Food and Drug Administration, which they felt wasnât moving quickly enough to allow them to develop their own tests. And so not only did you have the C.D.C. suddenly unable to disperse its tests to public health labs around the country, you also almost had this backup system that also couldnât get going initially. And so that was basically the story for the whole month of February, is that the state public health labs couldnât do their testing and neither could the hospitals and the academic medical centers that also wanted to get in the game and start testing.
michael barbaro
So catch us up from that original sin in the diagnostic testing in the U.S. At this point, how much diagnostic testing is underway in the U.S., and how does that compare to where everybody wants it to be?
katie thomas
Yeah. So things have picked up significantly since then. I mean, the whole month of March, finally, the F.D.A. â you know, they did make a policy change that allowed all of these labs to start developing and doing their own tests. Another thing that happened in the month of March is that these big testing companies that make these huge, high-capacity testing machines that enable labs to do thousands of coronavirus tests a day, they also completed their work on their tests and started selling them. And so there was a very big ramp up in the capacity for these labs to start doing the tests. But then, you know, as these labs started doing all these tests, they started to run into new problems.
michael barbaro
Like what?
katie thomas
Well, we started to see shortages of all kinds of different things. All of the supplies that you need in order to do these tests, suddenly they came under strain. The best example is probably the swabs that you need to conduct a test. Itâs this very long, skinny swab that almost looks like a Q-Tip, but itâs a very specialized swab that you stick all the way back into your nose to where your nose meets your throat. And those swabs are in demand globally because, obviously, this isnât just happening in the U.S. This is happening around the world.
michael barbaro
Of course.
katie thomas
One of the biggest companies that makes these swabs is actually an Italian company that is based in northern Italy, and thatâs where their factory is, as well.
michael barbaro
And of course, northern Italy is where there was a giant outbreak of the virus.
katie thomas
Thatâs right. So yeah, so in addition to the swabs, everything else started going into short supply, as well. There were the chemical reagents that are needed to do the tests. Thereâs the liquid that you insert the swab in to transport it to the lab. That started becoming short. Containers, the little vials that you stick the swab into, those started to become short. And then in addition, the shortage of masks and other personal protective equipment that weâve all heard about with hospitals and medical providers, the person whoâs doing the test also needs to have that protective wear, and so those shortages also started to affect the number of tests that providers could do. You know, if they didnât have masks, then they couldnât do a test, and if they didnât have enough swabs, then they couldnât do a test.
michael barbaro
Hm. So it turns out thereâs this kind of, like, unseen chain of items required to do testing, and even if you have plenty of tests you canât do the tests without each and every one of them.
katie thomas
Thatâs right.
michael barbaro
So at this point, how many diagnostic tests are being done in the U.S.?
katie thomas
Well, the number is likely going up, and the last couple of days itâs gone up significantly. You know, no one knows for sure exactly how many tests are being done, but the best estimates are that, you know, in the last several days, the U.S. has been doing about 250,000 tests a day.
michael barbaro
Now, Katie, is that a lot or a little, given that we are a nation of nearly 300 million people?
katie thomas
It sounds like a lot of tests, but actually, experts say that weâll have to do many times that in order to really reopen the country. Some say we may need to be doing a million or more in order to really know what weâre dealing with and to get a handle on the virus.
michael barbaro
Now, we keep hearing at the federal level that the U.S. has enough diagnostic tests, right? The Trump administration says at these daily news briefings, capacity has grown significantly, there is sufficient testing. So how does that square with what youâre describing?
katie thomas
Right. And thatâs the issue is that thereâs a big disconnect right now between the labs and what they theoretically could do in a day if they were sent X amount of tests, and the number of tests that hospitals that are actually testing the patients can do in a single day, given these ongoing shortages of everything from swabs to masks to the vials to send the swabs in.
michael barbaro
So the White House is accurate when it says, a lot more testing is possible. The only problem is that possible is not the same as having everything you need to do all the tests.
katie thomas
Thatâs right.
michael barbaro
So just to summarize where things are: When it comes to diagnostic tests of the coronavirus â this essential frontline weapon in telling governors and public health officials how many people have the virus â- once this major bottleneck at the C.D.C. got solved, then testing has really expanded, in part because the private sector was allowed to get involved. But thereâs still a major problem with the supply chain that basically means there isnât nearly as much testing done as everybody wants there to be done and thinks there needs to be done.
katie thomas
Thatâs right. Weâve come very far from where we were, and the picture is changing by the day. Weâre still not anywhere close to where most people feel like we need to be in order to really reopen the country.
\[music\]
And itâs right in the midst of that, of still ramping up these diagnostic tests, that weâre now kind of shifting our attention and focus toward this other big category of tests, which is the antibody test.
michael barbaro
The test that tells you if youâve already had the virus?
katie thomas
The test of whether youâve had the virus. Thatâs correct.
michael barbaro
And how, Katie, is that test going?
katie thomas
Well, that is proving to be just as complicated and problematic maybe as the diagnostic tests were.
michael barbaro
Weâll be right back.
Katie, what do we need to know about this second test, the antibody test?
katie thomas
Yeah. Well, we really need this new category of tests, the antibody tests, as we move forward and communities think about reopening, and thatâs for a number of reasons. One is just to get a feel for how far has the virus spread in your community. How many people have gotten it? Unlike the diagnostic tests which are kind of a moment in time, the antibody test tells you, have you ever had it, which is a valuable and slightly different piece of information. The other piece of this is, if we can accurately identify who has had it and who hasnât, it might help us figure out which health care workers can safely go back to work, and who can kind of rejoin our community.
michael barbaro
Right. And of course, which parts of the economy can reopen. We talked to our colleague Donald McNeil about this. This is the test that would help us distinguish the immune from the still susceptible, and the immune, if this test works, they become a very privileged class of people who get to do almost everything.
katie thomas
Right. I mean, theoretically, thatâs the idea.
michael barbaro
And so where are we in the development of that test?
katie thomas
So the F.D.A. and the federal government took a completely different approach when it came to the antibody tests. The F.D.A. came under criticism for having been too slow to allow the development of the diagnostic tests, and so when it came to the antibody tests, they almost overcorrected and they went in the other direction. And they went to all of the testing companies and basically said, if you want to develop an antibody test, go ahead, go for it. And rather than coming to us for approval before you can sell it, we are going to let you develop the tests, do your own validating, make sure that you are comfortable that your test works, and then once you are comfortable that it works, you can start selling the test. You donât need approval from us. And so, you know, the F.D.A. has said that theyâre now aware of dozens of companies that are selling or developing these antibody tests, and itâs really become almost like a wild, wild west of testing.
michael barbaro
So after having kind of held up the private sector when it came to the diagnostic test, this time they are supercharging the private sector on the antibody test, and putting a huge amount of trust in these corporations to do this and do it right.
katie thomas
Yes. Thatâs right.
michael barbaro
And so how has it gone?
katie thomas
Itâs been a really mixed bag. Thereâs just a huge variety of tests that are out there, and a huge variety of accuracy. In fact, there was a study that just came out by independent researchers that took a look at 14 of these tests, and it found that out of those 14 tests that they examined, only three delivered consistently reliable results.
michael barbaro
Wow. Three of 14 tests that are on the market already?
katie thomas
Thatâs right. Yeah. And some of the tests, a group of the tests, produced whatâs known as a false positive rate up to 16 percent of the time.
michael barbaro
And explain that. What does a false positive mean when it comes to an antibody test for the coronavirus?
katie thomas
Sure. So a false positive would be when the test incorrectly identifies somebody as having had the antibodies for the coronavirus when they didnât really have it â when they had never had the virus.
michael barbaro
And a 16 percent false positive rate â correct me if Iâm wrong â that sounds really bad for a test.
katie thomas
Yeah. I mean, it means that if you have 100 people, 16 of those people could be incorrectly identified as having had the virus and having antibodies to the virus.
michael barbaro
And that, of course, would be quite dangerous, because a false positive for the antibodies is basically the false understanding that you may be immune to the virus and would act accordingly â go out into the world, return to work, maybe not wear a mask.
katie thomas
Thatâs right. Thatâs right. It also would mean that, you know, if youâre the mayor or the governor or, you know, a public health leader, you also just donât have a very good picture of whatâs going on in your community and how many people have had the virus. And that could really be bad in a community where there arenât a lot of people that truly have the virus, because it could lead that community to think that theyâre at a different stage in this outbreak than they truly are, and it could lead them to make decisions about how to reopen and how to move forward in a way that really doesnât accurately reflect what the risks truly are.
michael barbaro
Right. Iâm thinking about places in rural America, for example, where if suddenly an antibody test were given to everyone in that community and infection rates were really low, in reality, a high false positive rate test might make everyone think, Oh, wow, weâve come out the other side of this epidemic and a lot of us are O.K., when in fact the virus just hasnât really washed over that community yet.
katie thomas
Thatâs right, when in fact itâs really an issue about the accuracy of the test versus the reality on the ground.
michael barbaro
Hm. So this government plan to avoid the problems of the diagnostic test rollout by taking a really hands-off approach and relying on private companies, that doesnât seem to have worked out very well. In fact, it seems, to a certain degree, to have backfired.
katie thomas
It has. I mean, you know, if you are a governor or a public health official in a community, you now have the job of trying to figure out which test you want to use and try and learn for yourself kind of whether it works or not.
michael barbaro
Are any of the tests highly reliable? Do any of the tests have very low false positive rates?
katie thomas
Yes. There are some tests that experts said are good and are accurate, and some of the really big testing companies â Abbott is one example â have recently come out with their own antibody test, and the feeling is that these tests are measurably better than some of the other ones that have come on the market.
michael barbaro
But it feels like overall, just to establish exactly where we are at this moment when it comes to testing, there are still significant problems with diagnostic tests because of those supply chain issues you talked about earlier, and we donât have anywhere near as reliable a set of antibody tests as everybody thinks we need.
katie thomas
Thatâs right. I mean, we basically havenât mastered either one of these tests.
michael barbaro
Katie, is testing just really hard in a public health emergency like the coronavirus, or do we just keep screwing this up kind of uniquely in the U.S.? Because now we have two examples â the diagnostic and the antibody test â where we canât quite seem to get it right when we very much need to get it right.
katie thomas
Yeah. I think some of this goes to the bigger picture of where we are at as a country with our health care system. Even before the pandemic, and even more so now that we are in a pandemic, the truth is is that our health care system is a huge jumble. Thereâs the federal government, thereâs all of the states, there are for-profit hospitals, there are nonprofit hospitals. Thereâs people who are covered by Medicare, by Medicaid, by insurance through their employer. Itâs all a big mix, and some would say a big mess, and this is all playing into testing, and who is testing, and which company do we use, and how do we get our supplies. So just to give you an example, say youâre a patient and youâre in the hospital and your doctor wants to give you a coronavirus test. They open up their computer and thereâs an electronic system that they use, and when they hit click to order a test, that test order will go out to the company that they happen to have a relationship with, say itâs LabCorp. Now, if LabCorp, at that moment of the crisis, has a week-long backlog, itâs not so easy for that hospital to quickly pivot to a different lab that might have capacity. So, you know, itâs very hard, for example, for that doctor, then, to get on the phone and maybe call 10 other labs in the area to check and see how quickly that they can process their test. And I can give you an example on the other side of that equation, which is, I know of a lab director who has all of that excess capacity. He could be processing hundreds more tests a day than he is, and yet heâs not getting calls from hospitals for their tests.
michael barbaro
Hmm. Youâre describing a situation in which the lack of any kind of centralized system in U.S. health care is really hampering our ability to test.
katie thomas
Right. I mean, in a pandemic, you really need to be able to move quickly and decisively, and, you know, I think weâve long known that our health care system is very fragmented, but weâre really seeing that play out in the example of testing. Whether itâs the supply chain issues, or getting antibody testing out there and accurate, itâs showing all of the kind of little ways that this system that we have is not quite up to the task and is slowing us down.
\[music\]
michael barbaro
Right. And the price of that is that it will take much longer for governors around the country and for local health officials to really get a grasp on where the virus is and to reopen our economy.
katie thomas
I think, unfortunately, thatâs right.
michael barbaro
Katie, thank you very much.
katie thomas
Thanks for having me.
michael barbaro
On Monday, the White House released new national guidelines on testing that put much of the burden on states rather than the federal government. Testing, the plan said, would be state-managed and locally executed. The federal government, the guidelines said, would be a, quote, âsupplier of last resort.â
Weâll be right back.
Hereâs what else you need to know today. On Monday, the U.S. Centers for Disease Control and Prevention named six new symptoms of the coronavirus in a move that reflects the unpredictable ways that the virus can affect individual patients. Previously, the C.D.C. listed just three symptoms â fever, cough, and shortness of breath. It has now included chills, repeated shaking with chills, muscle pain, headache, sore throat, and loss of taste or smell. And New York State has canceled its presidential primary, saying that with Bernie Sanders out of the race, the June 23 election would be purely symbolic and would detract from the stateâs response to the pandemic. Supporters of Sanders, whose name would have remained on the New York ballot, had pushed for the primary to be held, hoping to win more delegates that would give them greater influence over the partyâs platform at the Democratic National Convention.
Thatâs it for âThe Daily.â Iâm Michael Barbaro. See you tomorrow.
Listen · 26:29 min
Suited up in protective gear, the team worked in shifts of three to five hours in a sort of socially distanced factory line.
One researcher spotted the test with a blood sample, and another added the necessary chemical solutions; then two independent readers looked at the test, and a last person recorded the results. Still other team members analyzed the results, sometimes working through the night.
In the early hours of recent mornings, they handed the baton to Dr. Tyler Miller and his colleagues at Massachusetts General Hospital, who were conducting a slightly different analysis of three tests, including one evaluated in San Francisco.
The Bay Area team finished evaluating 12 tests in record time, less than a month. By comparison, the Chagas project required a team of three people working for more than a year just to compare four tests.
Having a study design already in hand helped speed the work, but there was one key difference. Decades of data have shown that Chagas disease elicits lifelong immunity. For this study, the team had no idea how quickly SARS-CoV-2 antibodies might turn up in the blood, or at what levels.
**\[****[Like the Science Times page on Facebook.](http://on.fb.me/1paTQ1h)***\| Sign up for the* **[Science Times newsletter.](http://nyti.ms/1MbHaRU)****\]**
New tests also usually compete with an established gold standard. Lacking such a standard, the team instead compared all the tests in a âhead-to-head bake-off to see whoâs the winner,â Dr. Hsu said.
Each test was evaluated with the same set of blood samples: from 80 people known to be infected with the coronavirus, at different points after infection; 108 samples donated before the pandemic; and 52 samples from people who were positive for other viral infections but had tested negative for SARS-CoV-2.
Tests made by Sure Biotech and Wondfo Biotech, along with an in-house Elisa test, produced the fewest false positives.
A test made by Bioperfectus detected antibodies in 100 percent of the infected samples, but only after three weeks of infection. None of the tests did better than 80 percent until that time period, which was longer than expected, Dr. Hsu said.
The lesson is that the tests are less likely to produce false negatives the longer ago the initial infection occurred, he said.
The tests were particularly variable when looking for a transient antibody that comes up soon after infection, called IgM, and more consistent in identifying a subsequent antibody, called IgG, that may signal longer-term immunity.
âYou can see that antibody levels rise at different points for every patient,â Dr. Hsu said. The tests performed best when the researchers assessed both types of antibodies together. None of the tests could say whether the presence of these antibodies means a person is protected from reinfection, however.
The results overall are promising, Dr. Marson added. âThere are multiple tests that have specificities greater than 95 percent.â
Rapid antibody tests are generally used to get a simple yes-no result, but the team assigned the positive results â which appear as bands on a test strip â a score from zero to six. They trained readers to interpret those results, and found their decisions often agreed and were supported by the more quantitative Elisa tests.
âIf you train the readers well, they can start to be reliable,â Dr. Marson said of rapid tests. âThat is critical to understand if these tests could ever be deployed.â
The team at Mass General set a higher bar for specificity; they considered a score of one for the intensity of a band to be a negative result, rather than a score of zero.
Perhaps because they eliminated the fainter bands â the ones most likely to be erroneous â their estimate of specificity for BioMedomics, the one test that was evaluated by both teams, was more than 99 percent, compared with the San Francisco teamâs estimate of 87 percent.
Other experts were skeptical of the scoring approach, however. âThatâs not really a method that would give you a real quantitation,â said Florian Krammer of the Icahn School of Medicine at Mount Sinai in New York.
Dr. Krammer has developed a two-step Elisa test that he said has 100 percent specificity and delivers a measure of the quantity of IgM and IgG antibodies a person has. Scoring a rapid testâs bands might offer some data for a scientific study, he said, âbut I would not make any decisions based on that.â
Dr. Krammer said false positives are less of an issue for assessing how widely the virus has spread in the population. If a test has a known false-positive rate, scientists can factor that into their calculations, he said.
But false positives become dangerous when making policy and personal decisions about who can go back to work. âYou donât want anybody back to work who has a false positive â thatâs the last thing you want to do,â Dr. Krammer said.
Scanwell Health, a Los Angeles-based start-up, has ordered millions of test kits from Innovita, a Chinese manufacturer, and has applied to the Food and Drug Administration to market the tests for at-home use.
In the new study, the Innovita test detected antibodies in 83 percent of infected people and yielded a false-positive rate of 4 percent.
Dr. Jack Jeng, chief medical officer of Scanwell Health, said the study looked at an earlier version of Innovitaâs test and not the ânewer, improved versionâ his company had ordered. âIt will be interesting to see how it performs,â he said.
Dr. Marson and his colleagues have acquired tests from nearly 100 manufacturers, and plan to continue comparing them. The scientists also hope to expand their sample set to include people who were mildly ill or did not feel ill at all, and to stratify their data by age and the presence of chronic conditions.
âThis is just the beginning,â Dr. Marson said. âOur goal would be to keep going till we feel thereâs adequate supply in the market.â
More on the coronavirus pandemic
[![]()R0, the Messy Metric That May Soon Shape Our Lives, Explained April 23, 2020](https://www.nytimes.com/2020/04/23/world/europe/coronavirus-R0-explainer.html)
[![]()A Coronavirus Death in Early February Was âProbably the Tip of an Icebergâ April 22, 2020](https://www.nytimes.com/2020/04/22/us/santa-clara-county-coronavirus-death.html)
[![]()China Imposes New Limits as Coronavirus Fears Return April 23, 2020](https://www.nytimes.com/2020/04/23/world/asia/china-coronavirus-new-infections.html)
[![]()Opinion Who Has Enough Cash to Get Through the Coronavirus Crisis?](https://www.nytimes.com/interactive/2020/04/23/opinion/emergency-savings-coronavirus.html)
[![]()As Coronavirus Eases, More Italians Say, âI Want Justiceâ April 23, 2020](https://www.nytimes.com/2020/04/23/world/europe/italy-coronavirus.html)
[Apoorva Mandavilli](https://www.nytimes.com/by/apoorva-mandavilli) is a reporter focusing on science and global health. She is the 2019 winner of the Victor Cohn Prize for Excellence in Medical Science Reporting.
A version of this article appears in print on April 26, 2020, Section A, Page 6 of the New York edition with the headline: False Positives: 11 of 14 Antibody Tests Are Unreliable, Researchers Find. [Order Reprints](https://nytimes.wrightsmedia.com/) \| [Todayâs Paper](https://www.nytimes.com/section/todayspaper) \| [Subscribe](https://www.nytimes.com/subscriptions/Multiproduct/lp8HYKU.html?campaignId=48JQY)
See more on: [Massachusetts General Hospital](https://www.nytimes.com/topic/organization/massachusetts-general-hospital), [University of California, San Francisco](https://www.nytimes.com/topic/university-of-california-san-francisco)
- Share full article
## Related Content
### [The Covid-19 Pandemic](https://www.nytimes.com/news-event/coronavirus)
- [As Kennedy Turns From Vaccines, MAHA Allies See a âBetrayalâ](https://www.nytimes.com/2026/03/02/health/kennedy-maha-vaccines.html)
Callaghan O'Hare for The New York Times
- [C.D.C.âs New Acting Director Draws Unexpected Praise From Agency Staff](https://www.nytimes.com/2026/02/26/health/cdc-bhattacharya-vaccinations-measles.html)
Eric Lee/The New York Times
- [Trump Administration Tells States It Aims to âReimagineâ Jobless Benefits](https://www.nytimes.com/2026/02/24/us/politics/trump-unemployment-benefits-fraud.html)
Tierney L. Cross/The New York Times
### [More in Health](https://www.nytimes.com/section/health)
- [From 2001: Beate Uhse, 81, Entrepreneur in the Business of Erotic Goods](https://www.nytimes.com/2026/03/06/world/europe/beate-uhse-dead.html)
Hesslefors/ullstein bild, via Getty Images
- [Banks Are Becoming Bulwarks for Vulnerable Seniors](https://www.nytimes.com/2026/02/28/health/scams-elderly-banks.html)
Federica Bordoni
- [Most Patients Keep Weight Off With Fewer GLP-1 Shots, Study Finds](https://www.nytimes.com/2026/03/04/health/glp1-weight-loss-dosing.html)
Kristian Thacker for The New York Times
- [They Helped Her Open a Weed Shop. Now Theyâre Suing for \$2.5 Million.](https://www.nytimes.com/2026/03/05/nyregion/cannabis-housingworks-new-york-dispute.html)
Kent J. Edwards for The New York Times
### Editorsâ Picks
- [âThe Pittâ Is Showing Us the Complicated Reality of Psychosis](https://www.nytimes.com/2026/02/26/well/mind/the-pitt-psychosis.html)
Warrick Page/HBO Max
- [My Sisterâs Crime Shattered Our Family. Do I Have to Help Her?](https://www.nytimes.com/2026/03/07/magazine/sisters-crime-family-ethics.html)
Illustration by Tomi Um
### Trending in The Times
- [Punching, Slamming, Screaming: A Chefâs Past Abuse Haunts Noma, the Worldâs Top-Rated Restaurant](https://www.nytimes.com/2026/03/07/dining/rene-redzepi-noma-abuse-allegations.html)
John McConnico for The New York Times
- [From 2018: Aretha Franklin, Indomitable âQueen of Soul,â Dies at 76](https://www.nytimes.com/2026/03/06/arts/music/aretha-franklin-dead.html)
Don Hogan Charles/The New York Times
- [Opinion: There Is One Crucial Reason Weâre Talking About Boots on the Ground](https://www.nytimes.com/2026/03/07/opinion/trump-iran-nuclear-weapons-enriched-uranium-war.html)
Illustration by Sam Whitney/The New York Times
- [The State of U.S. Markets](https://www.nytimes.com/video/us/100000010755999/the-state-of-us-markets.html)
- [I Make Connections. Hereâs What Iâm Actually Thinking.](https://www.nytimes.com/2026/03/07/insider/nyt-connections-game-writer-wyna-liu.html)
An Chen
- [At Least 6 Dead as Tornadoes Slam Michigan and Oklahoma](https://www.nytimes.com/2026/03/06/weather/storm-forecast-missouri-kansas-oklahoma.html)
Lindsey Whitaker
- [A Schools Chief So Charming That Los Angeles Overlooked His Red Flags](https://www.nytimes.com/2026/03/07/us/alberto-carvalho-lausd-scandals.html)
Philip Cheung for The New York Times
- [A Head of State, a Rock Star and Oprah Walk Into a Palace](https://www.nytimes.com/2026/03/06/style/stella-mccartney-legion-dhonneur-emmanuel-macron-paris.html)
Matteo Prandoni/BFA.com
- [Their Favorite Projects? Inventing Cocktails and Card Games.](https://www.nytimes.com/2026/03/06/style/alelli-tanghal-jai-lennard-wedding.html)
Artu Nepomuceno
- [Rebecca Solnit Says the Leftâs Next Hero Is Already Here](https://www.nytimes.com/2026/03/07/magazine/rebecca-solnit-interview.html)
Devin Oktar Yalkin for The New York Times
Advertisement
[SKIP ADVERTISEMENT](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#after-bottom)
## Site Index
[Go to Home Page »](https://www.nytimes.com/)
News
- [Home Page](https://www.nytimes.com/)
- [U.S.](https://www.nytimes.com/section/us)
- [World](https://www.nytimes.com/section/world)
- [Politics](https://www.nytimes.com/section/politics)
- [New York](https://www.nytimes.com/section/nyregion)
- [Education](https://www.nytimes.com/section/education)
- [Sports](https://www.nytimes.com/section/sports)
- [Business](https://www.nytimes.com/section/business)
- [Tech](https://www.nytimes.com/section/technology)
- [Science](https://www.nytimes.com/section/science)
- [Weather](https://www.nytimes.com/section/weather)
- [The Great Read](https://www.nytimes.com/spotlight/the-great-read)
- [Obituaries](https://www.nytimes.com/section/obituaries)
- [Headway](https://www.nytimes.com/section/headway)
- [Visual Investigations](https://www.nytimes.com/spotlight/visual-investigations)
- [The Magazine](https://www.nytimes.com/section/magazine)
Arts
- [Book Review](https://www.nytimes.com/section/books/review)
- [Best Sellers Book List](https://www.nytimes.com/books/best-sellers/)
- [Dance](https://www.nytimes.com/section/arts/dance)
- [Movies](https://www.nytimes.com/section/movies)
- [Music](https://www.nytimes.com/section/arts/music)
- [Pop Culture](https://www.nytimes.com/spotlight/pop-culture)
- [Television](https://www.nytimes.com/section/arts/television)
- [Theater](https://www.nytimes.com/section/theater)
- [Visual Arts](https://www.nytimes.com/section/arts/design)
Lifestyle
- [Health](https://www.nytimes.com/section/health)
- [Well](https://www.nytimes.com/section/well)
- [Food](https://www.nytimes.com/section/food)
- [Restaurant Reviews](https://www.nytimes.com/reviews/dining)
- [Love](https://www.nytimes.com/section/fashion/weddings)
- [Travel](https://www.nytimes.com/section/travel)
- [Style](https://www.nytimes.com/section/style)
- [Fashion](https://www.nytimes.com/section/fashion)
- [Real Estate](https://www.nytimes.com/section/realestate)
- [T Magazine](https://www.nytimes.com/section/t-magazine)
Opinion
- [Today's Opinion](https://www.nytimes.com/section/opinion)
- [Columnists](https://www.nytimes.com/section/opinion/columnists)
- [Editorials](https://www.nytimes.com/section/opinion/editorials)
- [Guest Essays](https://www.nytimes.com/section/opinion/contributors)
- [Op-Docs](https://www.nytimes.com/column/op-docs)
- [Letters](https://www.nytimes.com/section/opinion/letters)
- [Sunday Opinion](https://www.nytimes.com/section/opinion/sunday)
- [Opinion Video](https://www.nytimes.com/spotlight/opinion-video)
- [Opinion Audio](https://www.nytimes.com/series/opinion-audio)
More
- [Audio](https://www.nytimes.com/spotlight/podcasts)
- [Games](https://www.nytimes.com/crosswords)
- [Cooking](https://cooking.nytimes.com/)
- [Wirecutter](https://www.nytimes.com/wirecutter/)
- [The Athletic](https://www.nytimes.com/athletic/)
- [Jobs](https://www.nytimes.com/section/jobs)
- [Video](https://www.nytimes.com/video)
- [Graphics](https://www.nytimes.com/spotlight/graphics)
- [Trending](https://www.nytimes.com/trending/)
- [Live Events](https://www.nytimes.com/spotlight/nyt-events)
- [Corrections](https://www.nytimes.com/section/corrections)
- [Reader Center](https://www.nytimes.com/section/reader-center)
- [TimesMachine](https://timesmachine.nytimes.com/browser)
- [The Learning Network](https://www.nytimes.com/section/learning)
- [School of The NYT](https://nytedu.com/)
- [inEducation](https://www.nytimes.com/spotlight/nytimesineducation)
### News
- [Home Page](https://www.nytimes.com/)
- [U.S.](https://www.nytimes.com/section/us)
- [World](https://www.nytimes.com/section/world)
- [Politics](https://www.nytimes.com/section/politics)
- [New York](https://www.nytimes.com/section/nyregion)
- [Education](https://www.nytimes.com/section/education)
- [Sports](https://www.nytimes.com/section/sports)
- [Business](https://www.nytimes.com/section/business)
- [Tech](https://www.nytimes.com/section/technology)
- [Science](https://www.nytimes.com/section/science)
- [Weather](https://www.nytimes.com/section/weather)
- [The Great Read](https://www.nytimes.com/spotlight/the-great-read)
- [Obituaries](https://www.nytimes.com/section/obituaries)
- [Headway](https://www.nytimes.com/section/headway)
- [Visual Investigations](https://www.nytimes.com/spotlight/visual-investigations)
- [The Magazine](https://www.nytimes.com/section/magazine)
### Arts
- [Book Review](https://www.nytimes.com/section/books/review)
- [Best Sellers Book List](https://www.nytimes.com/books/best-sellers/)
- [Dance](https://www.nytimes.com/section/arts/dance)
- [Movies](https://www.nytimes.com/section/movies)
- [Music](https://www.nytimes.com/section/arts/music)
- [Pop Culture](https://www.nytimes.com/spotlight/pop-culture)
- [Television](https://www.nytimes.com/section/arts/television)
- [Theater](https://www.nytimes.com/section/theater)
- [Visual Arts](https://www.nytimes.com/section/arts/design)
### Lifestyle
- [Health](https://www.nytimes.com/section/health)
- [Well](https://www.nytimes.com/section/well)
- [Food](https://www.nytimes.com/section/food)
- [Restaurant Reviews](https://www.nytimes.com/reviews/dining)
- [Love](https://www.nytimes.com/section/fashion/weddings)
- [Travel](https://www.nytimes.com/section/travel)
- [Style](https://www.nytimes.com/section/style)
- [Fashion](https://www.nytimes.com/section/fashion)
- [Real Estate](https://www.nytimes.com/section/realestate)
- [T Magazine](https://www.nytimes.com/section/t-magazine)
### Opinion
- [Today's Opinion](https://www.nytimes.com/section/opinion)
- [Columnists](https://www.nytimes.com/section/opinion/columnists)
- [Editorials](https://www.nytimes.com/section/opinion/editorials)
- [Guest Essays](https://www.nytimes.com/section/opinion/contributors)
- [Op-Docs](https://www.nytimes.com/column/op-docs)
- [Letters](https://www.nytimes.com/section/opinion/letters)
- [Sunday Opinion](https://www.nytimes.com/section/opinion/sunday)
- [Opinion Video](https://www.nytimes.com/spotlight/opinion-video)
- [Opinion Audio](https://www.nytimes.com/series/opinion-audio)
### More
- [Audio](https://www.nytimes.com/spotlight/podcasts)
- [Games](https://www.nytimes.com/crosswords)
- [Cooking](https://cooking.nytimes.com/)
- [Wirecutter](https://www.nytimes.com/wirecutter/)
- [The Athletic](https://www.nytimes.com/athletic/)
- [Jobs](https://www.nytimes.com/section/jobs)
- [Video](https://www.nytimes.com/video)
- [Graphics](https://www.nytimes.com/spotlight/graphics)
- [Trending](https://www.nytimes.com/trending/)
- [Live Events](https://www.nytimes.com/spotlight/nyt-events)
- [Corrections](https://www.nytimes.com/section/corrections)
- [Reader Center](https://www.nytimes.com/section/reader-center)
- [TimesMachine](https://timesmachine.nytimes.com/browser)
- [The Learning Network](https://www.nytimes.com/section/learning)
- [School of The NYT](https://nytedu.com/)
- [inEducation](https://www.nytimes.com/spotlight/nytimesineducation)
### Account
- [Subscribe](https://www.nytimes.com/subscription)
- [Manage My Account](https://www.nytimes.com/account)
- [Home Delivery](https://www.nytimes.com/subscription/home-delivery)
- [Gift Subscriptions](https://www.nytimes.com/gift)
- [Group Subscriptions](https://www.nytimes.com/subscription/groups?Pardot_Campaign_Code_Form_Input=89FQX)
- [Gift Articles](https://www.nytimes.com/gift-articles)
- [Email Newsletters](https://www.nytimes.com/newsletters)
- [NYT Licensing](https://nytlicensing.com/)
- [Replica Edition](https://nytimes.pressreader.com/)
- [Times Store](https://store.nytimes.com/)
## Site Information Navigation
- [© 2026 The New York Times Company](https://help.nytimes.com/hc/en-us/articles/115014792127-Copyright-Notice)
- [NYTCo](https://www.nytco.com/)
- [Contact Us](https://help.nytimes.com/hc/en-us/articles/115015385887-Contact-The-New-York-Times)
- [Accessibility](https://help.nytimes.com/hc/en-us/articles/115015727108-Accessibility)
- [Work with us](https://www.nytco.com/careers/)
- [Advertise](https://advertising.nytimes.com/)
- [T Brand Studio](https://advertising.nytimes.com/custom-content/)
- [Privacy Policy](https://help.nytimes.com/hc/en-us/articles/10940941449492-The-New-York-Times-Company-Privacy-Policy)
- [Cookie Policy](https://www.nytimes.com/privacy/cookie-policy)
- [Terms of Service](https://help.nytimes.com/hc/en-us/articles/115014893428-Terms-of-Service)
- [Terms of Sale](https://help.nytimes.com/hc/en-us/articles/115014893968-Terms-of-Sale)
- [Site Map](https://www.nytimes.com/sitemap/)
- [Canada](https://www.nytimes.com/ca/)
- [International](https://www.nytimes.com/international/)
- [Help](https://help.nytimes.com/hc/en-us)
- [Subscriptions](https://www.nytimes.com/subscription?campaignId=37WXW) |
| Readable Markdown | Advertisement
[SKIP ADVERTISEMENT](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#after-top)
A team of scientists worked around the clock to evaluate 14 antibody tests. A few worked as advertised. Most did not.
From left, Dr. Caryn Bern, Dr. Alexander Marson, Patrick Hsu and Dr. Jeffrey Whitman, who have helped lead an effort to assess antibody tests for the coronavirus.Credit...Anastasiia Sapon for The New York Times
Published April 24, 2020Updated Aug. 19, 2020
The researchers worked around the clock, in shifts of three to five hours, hoping to stave off weariness and keep their minds sharp for the delicate task.
They set up lines of laboratory volunteers: medical residents, postdoctoral students, even experienced veterans of science, each handling a specific task. They checked and rechecked their data, as if the world were depending on it. Because in some ways, it is.
For the past few weeks, more than 50 scientists have been working diligently to do something that the Food and Drug Administration mostly has not: Verifying that 14 [coronavirus antibody tests](https://www.nytimes.com/2020/08/19/nyregion/new-york-city-antibody-test.html) now on the market actually deliver accurate results.
These tests are crucial to reopening the economy, but public health experts have raised urgent concerns about their quality. The new research, completed just days ago and posted online Friday, confirmed some of those fears: Of the 14 tests, only three [delivered consistently reliable results](https://covidtestingproject.org/). Even the best had some flaws.
The research has not been peer-reviewed and is subject to revision. But the results are already raising difficult questions about the course of the epidemic.
Surveys of residents in the Bay Area, Los Angeles and New York this week found that substantial percentages tested positive for antibodies to SARS-CoV-2, the official name of the new [coronavirus](https://www.nytimes.com/2021/03/26/health/coronavirus-covid-testing.html). In New York City, the figure was said to be as high as 21 percent. Elsewhere, it was closer to 3 percent.
The idea that many residents in some parts of the country have already been exposed to the virus has wide implications. At the least, the finding could greatly complicate plans to reopen the economy.
Already Americans are scrambling to take [antibody](https://www.nytimes.com/2020/06/18/health/coronavirus-antibodies.html) tests to see if they might escape lockdowns. Public health experts are wondering if those with positive results might be allowed to return to work.
But these tactics mean nothing if the [test](https://www.nytimes.com/2020/05/05/health/crispr-coronavirus-covid-test.html) results canât be trusted.
In the new research, researchers found that only one of the tests never delivered a so-called false positive â that is, it never mistakenly signaled antibodies in people who did not have them.
Two other tests did not deliver false-positive results 99 percent of the time.
But the converse was not true. Even these three tests detected antibodies in infected people only 90 percent of the time, at best.
The false-positive metric is particularly important. The result may lead people to believe themselves immune to the virus when they are not, and to put themselves in danger by abandoning social distancing and other protective measures.
It is also the result on which scientists are most divided.
âThere are multiple tests that look reasonable and promising,â said Dr. Alexander Marson, an immunologist at the University of California, San Francisco, and one of the projectâs leaders. âThatâs some reason for optimism.â
Dr. Marson is also an investigator in the Chan Zuckerberg Biohub, which partly funded the study.
Other scientists were less sanguine than Dr. Marson. Four of the tests produced false-positive rates ranging from 11 percent to 16 percent; many of the rest hovered around 5 percent.
âThose numbers are just unacceptable,â said Scott Hensley, a microbiologist at the University of Pennsylvania. âThe tone of the paper is, âLook how good the tests are.â But I look at these data, and I donât really see that.â
The proportion of people in the United States who have been exposed to the coronavirus is likely to be 5 percent or less, Dr. Hensley said. âIf your kit has a 3 percent false-positive, how do you interpret that? Itâs basically impossible,â he said. âIf your kit has 14 percent false positive, itâs useless.â
Dr. Hensley said the study nonetheless was well designed and the results pressing, given the sudden proliferation of antibody tests on the market and the push to use them to lift lockdowns.
âI think this is exactly the kind of study that we need right now,â he said.
Dr. Marson and his colleagues said they were drawn to the study for that very reason.
As universities in the Bay Area shut down all research not related to the coronavirus, some researchers began focusing on ways to improve diagnostic tests for SARS-CoV-2.
Dr. Marson and his collaborator, Patrick Hsu, a bioengineer at the University of California, Berkeley, anticipated that antibody tests would also face questions about quality.
In mid-March, Dr. Hsu heard that a friend, a venture capitalist who owns a network of 1,000 community clinics in the New York area, had ordered thousands of rapid antibody tests. Investors and entrepreneurs seemed to be distributing them around San Francisco, too.
âI realized, âGosh this is really the Wild West,ââ Dr. Hsu said. âWe needed to figure out which of these would really work.â
The duo recruited Dr. Jeffrey Whitman and Dr. Caryn Bern, who last year published an [analysis of antibody tests](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6879282/) for Chagas disease. Other graduate students and postdoctoral fellows volunteered to help perform the evaluations.
The team began with a modified version of the method Dr. Whitman had devised to validate Chagas tests. The researchers created a biosafety-certified space, obtained the needed approvals and procured hundreds of blood samples from two Bay Area hospitals.
They also purchased tests from Chinese manufacturers, clearing customs regulations and sometimes accepting Uber deliveries in the middle of the night.
In all, the investigators analyzed 10 rapid tests that deliver a yes-no signal for antibodies, and two tests using a lab technique known as Elisa that indicate the amount of antibodies present and are generally considered to be more reliable.
Image
Tori Yamamoto, left, and Ujjwal Rathore, who worked with Elisa antibody tests. The photo was taken with a phone in a sterile container.Credit...Joe Hiatt/University of California, San Francisco
### Listen to âThe Dailyâ: The State of Testing
Rigorous testing has been key to reopening economies in Asia. So why is the U.S. lagging behind in administering tests?
transcript
0:00/26:29
\-26:29
transcript
## Listen to âThe Dailyâ: The State of Testing
### Hosted by Michael Barbaro, produced by Rachel Quester and Jessica Cheung, and edited by M.J. Davis Lin
#### Rigorous testing has been key to reopening economies in Asia. So why is the U.S. lagging behind in administering tests?
archived recording (gov. andrew cuomo)
Everybody wants to reopen.
So how do you actually do that intelligently? Well, you have to test.
\[music\]
michael barbaro
From The New York Times, Iâm Michael Barbaro. This is âThe Daily.â Today, as governors across the country debate when and how to reopen their economies â
archived recording 1
We are nowhere near where we need to be with testing supplies.
archived recording 2
Yeah, look, weâre nowhere near where we need to be on testing. Letâs just be straight with folks.
archived recording 3
You know, our testing is increasing, but itâs not increasing nearly fast enough.
michael barbaro
â they say that the single biggest impediment is their inability to measure and monitor infection rates in their communities.
archived recording 1
Weâve been fighting for testing.
archived recording 2
We need to be doing robust testing in order to really assess when and how itâs safe to resume life.
michael barbaro
Katie Thomas on the state of testing. Itâs Tuesday, April 28.
Katie, when state officials talk about testing as a decisive factor in whether and when to reopen their economies, what do they mean?
katie thomas
Well, for the governors, this is really an essential tool. Itâs what they are going to need to rely on if theyâre going to reopen their economy and their communities. I mean, think of it like a fire department that doesnât have an essential tool like hoses. They canât put out fires. And the governors, if they canât have consistent and widespread testing throughout their states, then, you know, they canât see when a new hot spot is popping up or infections are rising, and whether theyâre successfully beating the virus or not.
michael barbaro
And exactly what kind of testing are we talking about here?
katie thomas
Well, thereâs two kinds of tests. The first one is the one that many of us have been talking about for a while, the diagnostic testing, which actually tests for pieces of the actual virus, and that will tell you and your doctors whether you are actively infected with the virus and whether you have it. Then the second group of testing, which is really kind of just getting underway right now, is called antibody testing. Thatâs the idea that after you have had the virus and youâve recovered, your body has developed antibodies, which help fight off the virus. Generally â we donât know for sure, science still doesnât know, but people are pretty much operating on the assumption that if you have these antibodies in your system, then you are immune, at least for now, from getting infected again from this coronavirus.
michael barbaro
Gotcha. So one of these tests says, youâve got the virus. The other says, youâve had the virus. Letâs start with the diagnostic test, right, because that is the test that people talk to us about when they talk about flattening the curve and limiting the spread. So where do things stand with that test?
katie thomas
So as you probably remember, things got off to a pretty bad start in the U.S. with diagnostic testing back in January. The C.D.C., whose job it is to initially get things rolling with developing a test and then sending it out to all the public health labs around the country so that they can start testing, encountered basically a manufacturing problem as they were scaling up the tests and mailing them out. As they mailed out that first batch to the public health labs around the country and the labs started testing them to make sure that they were correct, they quickly realized that they had a problem. And what happened is some contamination got into the tests that basically made it so that they revealed an invalid result, and so they couldnât be relied upon.
michael barbaro
Mm-hmm.
katie thomas
So this set back testing in the country significantly and for weeks, because basically those public health labs then couldnât do the testing that they had planned on doing, and almost all of the testing in the country for the month of February was only done through the C.D.C. lab.
michael barbaro
Right, creating a huge bottleneck at a crucial moment when the virus is spreading all over the country.
katie thomas
Exactly. And while the C.D.C. was scrambling to fix the problem, this whole other system of private labs, university and hospital labs that were ready and who wanted to develop their own tests, they were slowed down, they said, by the Food and Drug Administration, which they felt wasnât moving quickly enough to allow them to develop their own tests. And so not only did you have the C.D.C. suddenly unable to disperse its tests to public health labs around the country, you also almost had this backup system that also couldnât get going initially. And so that was basically the story for the whole month of February, is that the state public health labs couldnât do their testing and neither could the hospitals and the academic medical centers that also wanted to get in the game and start testing.
michael barbaro
So catch us up from that original sin in the diagnostic testing in the U.S. At this point, how much diagnostic testing is underway in the U.S., and how does that compare to where everybody wants it to be?
katie thomas
Yeah. So things have picked up significantly since then. I mean, the whole month of March, finally, the F.D.A. â you know, they did make a policy change that allowed all of these labs to start developing and doing their own tests. Another thing that happened in the month of March is that these big testing companies that make these huge, high-capacity testing machines that enable labs to do thousands of coronavirus tests a day, they also completed their work on their tests and started selling them. And so there was a very big ramp up in the capacity for these labs to start doing the tests. But then, you know, as these labs started doing all these tests, they started to run into new problems.
michael barbaro
Like what?
katie thomas
Well, we started to see shortages of all kinds of different things. All of the supplies that you need in order to do these tests, suddenly they came under strain. The best example is probably the swabs that you need to conduct a test. Itâs this very long, skinny swab that almost looks like a Q-Tip, but itâs a very specialized swab that you stick all the way back into your nose to where your nose meets your throat. And those swabs are in demand globally because, obviously, this isnât just happening in the U.S. This is happening around the world.
michael barbaro
Of course.
katie thomas
One of the biggest companies that makes these swabs is actually an Italian company that is based in northern Italy, and thatâs where their factory is, as well.
michael barbaro
And of course, northern Italy is where there was a giant outbreak of the virus.
katie thomas
Thatâs right. So yeah, so in addition to the swabs, everything else started going into short supply, as well. There were the chemical reagents that are needed to do the tests. Thereâs the liquid that you insert the swab in to transport it to the lab. That started becoming short. Containers, the little vials that you stick the swab into, those started to become short. And then in addition, the shortage of masks and other personal protective equipment that weâve all heard about with hospitals and medical providers, the person whoâs doing the test also needs to have that protective wear, and so those shortages also started to affect the number of tests that providers could do. You know, if they didnât have masks, then they couldnât do a test, and if they didnât have enough swabs, then they couldnât do a test.
michael barbaro
Hm. So it turns out thereâs this kind of, like, unseen chain of items required to do testing, and even if you have plenty of tests you canât do the tests without each and every one of them.
katie thomas
Thatâs right.
michael barbaro
So at this point, how many diagnostic tests are being done in the U.S.?
katie thomas
Well, the number is likely going up, and the last couple of days itâs gone up significantly. You know, no one knows for sure exactly how many tests are being done, but the best estimates are that, you know, in the last several days, the U.S. has been doing about 250,000 tests a day.
michael barbaro
Now, Katie, is that a lot or a little, given that we are a nation of nearly 300 million people?
katie thomas
It sounds like a lot of tests, but actually, experts say that weâll have to do many times that in order to really reopen the country. Some say we may need to be doing a million or more in order to really know what weâre dealing with and to get a handle on the virus.
michael barbaro
Now, we keep hearing at the federal level that the U.S. has enough diagnostic tests, right? The Trump administration says at these daily news briefings, capacity has grown significantly, there is sufficient testing. So how does that square with what youâre describing?
katie thomas
Right. And thatâs the issue is that thereâs a big disconnect right now between the labs and what they theoretically could do in a day if they were sent X amount of tests, and the number of tests that hospitals that are actually testing the patients can do in a single day, given these ongoing shortages of everything from swabs to masks to the vials to send the swabs in.
michael barbaro
So the White House is accurate when it says, a lot more testing is possible. The only problem is that possible is not the same as having everything you need to do all the tests.
katie thomas
Thatâs right.
michael barbaro
So just to summarize where things are: When it comes to diagnostic tests of the coronavirus â this essential frontline weapon in telling governors and public health officials how many people have the virus â- once this major bottleneck at the C.D.C. got solved, then testing has really expanded, in part because the private sector was allowed to get involved. But thereâs still a major problem with the supply chain that basically means there isnât nearly as much testing done as everybody wants there to be done and thinks there needs to be done.
katie thomas
Thatâs right. Weâve come very far from where we were, and the picture is changing by the day. Weâre still not anywhere close to where most people feel like we need to be in order to really reopen the country.
\[music\]
And itâs right in the midst of that, of still ramping up these diagnostic tests, that weâre now kind of shifting our attention and focus toward this other big category of tests, which is the antibody test.
michael barbaro
The test that tells you if youâve already had the virus?
katie thomas
The test of whether youâve had the virus. Thatâs correct.
michael barbaro
And how, Katie, is that test going?
katie thomas
Well, that is proving to be just as complicated and problematic maybe as the diagnostic tests were.
michael barbaro
Weâll be right back.
Katie, what do we need to know about this second test, the antibody test?
katie thomas
Yeah. Well, we really need this new category of tests, the antibody tests, as we move forward and communities think about reopening, and thatâs for a number of reasons. One is just to get a feel for how far has the virus spread in your community. How many people have gotten it? Unlike the diagnostic tests which are kind of a moment in time, the antibody test tells you, have you ever had it, which is a valuable and slightly different piece of information. The other piece of this is, if we can accurately identify who has had it and who hasnât, it might help us figure out which health care workers can safely go back to work, and who can kind of rejoin our community.
michael barbaro
Right. And of course, which parts of the economy can reopen. We talked to our colleague Donald McNeil about this. This is the test that would help us distinguish the immune from the still susceptible, and the immune, if this test works, they become a very privileged class of people who get to do almost everything.
katie thomas
Right. I mean, theoretically, thatâs the idea.
michael barbaro
And so where are we in the development of that test?
katie thomas
So the F.D.A. and the federal government took a completely different approach when it came to the antibody tests. The F.D.A. came under criticism for having been too slow to allow the development of the diagnostic tests, and so when it came to the antibody tests, they almost overcorrected and they went in the other direction. And they went to all of the testing companies and basically said, if you want to develop an antibody test, go ahead, go for it. And rather than coming to us for approval before you can sell it, we are going to let you develop the tests, do your own validating, make sure that you are comfortable that your test works, and then once you are comfortable that it works, you can start selling the test. You donât need approval from us. And so, you know, the F.D.A. has said that theyâre now aware of dozens of companies that are selling or developing these antibody tests, and itâs really become almost like a wild, wild west of testing.
michael barbaro
So after having kind of held up the private sector when it came to the diagnostic test, this time they are supercharging the private sector on the antibody test, and putting a huge amount of trust in these corporations to do this and do it right.
katie thomas
Yes. Thatâs right.
michael barbaro
And so how has it gone?
katie thomas
Itâs been a really mixed bag. Thereâs just a huge variety of tests that are out there, and a huge variety of accuracy. In fact, there was a study that just came out by independent researchers that took a look at 14 of these tests, and it found that out of those 14 tests that they examined, only three delivered consistently reliable results.
michael barbaro
Wow. Three of 14 tests that are on the market already?
katie thomas
Thatâs right. Yeah. And some of the tests, a group of the tests, produced whatâs known as a false positive rate up to 16 percent of the time.
michael barbaro
And explain that. What does a false positive mean when it comes to an antibody test for the coronavirus?
katie thomas
Sure. So a false positive would be when the test incorrectly identifies somebody as having had the antibodies for the coronavirus when they didnât really have it â when they had never had the virus.
michael barbaro
And a 16 percent false positive rate â correct me if Iâm wrong â that sounds really bad for a test.
katie thomas
Yeah. I mean, it means that if you have 100 people, 16 of those people could be incorrectly identified as having had the virus and having antibodies to the virus.
michael barbaro
And that, of course, would be quite dangerous, because a false positive for the antibodies is basically the false understanding that you may be immune to the virus and would act accordingly â go out into the world, return to work, maybe not wear a mask.
katie thomas
Thatâs right. Thatâs right. It also would mean that, you know, if youâre the mayor or the governor or, you know, a public health leader, you also just donât have a very good picture of whatâs going on in your community and how many people have had the virus. And that could really be bad in a community where there arenât a lot of people that truly have the virus, because it could lead that community to think that theyâre at a different stage in this outbreak than they truly are, and it could lead them to make decisions about how to reopen and how to move forward in a way that really doesnât accurately reflect what the risks truly are.
michael barbaro
Right. Iâm thinking about places in rural America, for example, where if suddenly an antibody test were given to everyone in that community and infection rates were really low, in reality, a high false positive rate test might make everyone think, Oh, wow, weâve come out the other side of this epidemic and a lot of us are O.K., when in fact the virus just hasnât really washed over that community yet.
katie thomas
Thatâs right, when in fact itâs really an issue about the accuracy of the test versus the reality on the ground.
michael barbaro
Hm. So this government plan to avoid the problems of the diagnostic test rollout by taking a really hands-off approach and relying on private companies, that doesnât seem to have worked out very well. In fact, it seems, to a certain degree, to have backfired.
katie thomas
It has. I mean, you know, if you are a governor or a public health official in a community, you now have the job of trying to figure out which test you want to use and try and learn for yourself kind of whether it works or not.
michael barbaro
Are any of the tests highly reliable? Do any of the tests have very low false positive rates?
katie thomas
Yes. There are some tests that experts said are good and are accurate, and some of the really big testing companies â Abbott is one example â have recently come out with their own antibody test, and the feeling is that these tests are measurably better than some of the other ones that have come on the market.
michael barbaro
But it feels like overall, just to establish exactly where we are at this moment when it comes to testing, there are still significant problems with diagnostic tests because of those supply chain issues you talked about earlier, and we donât have anywhere near as reliable a set of antibody tests as everybody thinks we need.
katie thomas
Thatâs right. I mean, we basically havenât mastered either one of these tests.
michael barbaro
Katie, is testing just really hard in a public health emergency like the coronavirus, or do we just keep screwing this up kind of uniquely in the U.S.? Because now we have two examples â the diagnostic and the antibody test â where we canât quite seem to get it right when we very much need to get it right.
katie thomas
Yeah. I think some of this goes to the bigger picture of where we are at as a country with our health care system. Even before the pandemic, and even more so now that we are in a pandemic, the truth is is that our health care system is a huge jumble. Thereâs the federal government, thereâs all of the states, there are for-profit hospitals, there are nonprofit hospitals. Thereâs people who are covered by Medicare, by Medicaid, by insurance through their employer. Itâs all a big mix, and some would say a big mess, and this is all playing into testing, and who is testing, and which company do we use, and how do we get our supplies. So just to give you an example, say youâre a patient and youâre in the hospital and your doctor wants to give you a coronavirus test. They open up their computer and thereâs an electronic system that they use, and when they hit click to order a test, that test order will go out to the company that they happen to have a relationship with, say itâs LabCorp. Now, if LabCorp, at that moment of the crisis, has a week-long backlog, itâs not so easy for that hospital to quickly pivot to a different lab that might have capacity. So, you know, itâs very hard, for example, for that doctor, then, to get on the phone and maybe call 10 other labs in the area to check and see how quickly that they can process their test. And I can give you an example on the other side of that equation, which is, I know of a lab director who has all of that excess capacity. He could be processing hundreds more tests a day than he is, and yet heâs not getting calls from hospitals for their tests.
michael barbaro
Hmm. Youâre describing a situation in which the lack of any kind of centralized system in U.S. health care is really hampering our ability to test.
katie thomas
Right. I mean, in a pandemic, you really need to be able to move quickly and decisively, and, you know, I think weâve long known that our health care system is very fragmented, but weâre really seeing that play out in the example of testing. Whether itâs the supply chain issues, or getting antibody testing out there and accurate, itâs showing all of the kind of little ways that this system that we have is not quite up to the task and is slowing us down.
\[music\]
michael barbaro
Right. And the price of that is that it will take much longer for governors around the country and for local health officials to really get a grasp on where the virus is and to reopen our economy.
katie thomas
I think, unfortunately, thatâs right.
michael barbaro
Katie, thank you very much.
katie thomas
Thanks for having me.
michael barbaro
On Monday, the White House released new national guidelines on testing that put much of the burden on states rather than the federal government. Testing, the plan said, would be state-managed and locally executed. The federal government, the guidelines said, would be a, quote, âsupplier of last resort.â
Weâll be right back.
Hereâs what else you need to know today. On Monday, the U.S. Centers for Disease Control and Prevention named six new symptoms of the coronavirus in a move that reflects the unpredictable ways that the virus can affect individual patients. Previously, the C.D.C. listed just three symptoms â fever, cough, and shortness of breath. It has now included chills, repeated shaking with chills, muscle pain, headache, sore throat, and loss of taste or smell. And New York State has canceled its presidential primary, saying that with Bernie Sanders out of the race, the June 23 election would be purely symbolic and would detract from the stateâs response to the pandemic. Supporters of Sanders, whose name would have remained on the New York ballot, had pushed for the primary to be held, hoping to win more delegates that would give them greater influence over the partyâs platform at the Democratic National Convention.
Thatâs it for âThe Daily.â Iâm Michael Barbaro. See you tomorrow.
Listen · 26:29 min
Suited up in protective gear, the team worked in shifts of three to five hours in a sort of socially distanced factory line.
One researcher spotted the test with a blood sample, and another added the necessary chemical solutions; then two independent readers looked at the test, and a last person recorded the results. Still other team members analyzed the results, sometimes working through the night.
In the early hours of recent mornings, they handed the baton to Dr. Tyler Miller and his colleagues at Massachusetts General Hospital, who were conducting a slightly different analysis of three tests, including one evaluated in San Francisco.
The Bay Area team finished evaluating 12 tests in record time, less than a month. By comparison, the Chagas project required a team of three people working for more than a year just to compare four tests.
Having a study design already in hand helped speed the work, but there was one key difference. Decades of data have shown that Chagas disease elicits lifelong immunity. For this study, the team had no idea how quickly SARS-CoV-2 antibodies might turn up in the blood, or at what levels.
**\[****[Like the Science Times page on Facebook.](http://on.fb.me/1paTQ1h)***\| Sign up for the* **[Science Times newsletter.](http://nyti.ms/1MbHaRU)****\]**
New tests also usually compete with an established gold standard. Lacking such a standard, the team instead compared all the tests in a âhead-to-head bake-off to see whoâs the winner,â Dr. Hsu said.
Each test was evaluated with the same set of blood samples: from 80 people known to be infected with the coronavirus, at different points after infection; 108 samples donated before the pandemic; and 52 samples from people who were positive for other viral infections but had tested negative for SARS-CoV-2.
Tests made by Sure Biotech and Wondfo Biotech, along with an in-house Elisa test, produced the fewest false positives.
A test made by Bioperfectus detected antibodies in 100 percent of the infected samples, but only after three weeks of infection. None of the tests did better than 80 percent until that time period, which was longer than expected, Dr. Hsu said.
The lesson is that the tests are less likely to produce false negatives the longer ago the initial infection occurred, he said.
The tests were particularly variable when looking for a transient antibody that comes up soon after infection, called IgM, and more consistent in identifying a subsequent antibody, called IgG, that may signal longer-term immunity.
âYou can see that antibody levels rise at different points for every patient,â Dr. Hsu said. The tests performed best when the researchers assessed both types of antibodies together. None of the tests could say whether the presence of these antibodies means a person is protected from reinfection, however.
The results overall are promising, Dr. Marson added. âThere are multiple tests that have specificities greater than 95 percent.â
Rapid antibody tests are generally used to get a simple yes-no result, but the team assigned the positive results â which appear as bands on a test strip â a score from zero to six. They trained readers to interpret those results, and found their decisions often agreed and were supported by the more quantitative Elisa tests.
âIf you train the readers well, they can start to be reliable,â Dr. Marson said of rapid tests. âThat is critical to understand if these tests could ever be deployed.â
The team at Mass General set a higher bar for specificity; they considered a score of one for the intensity of a band to be a negative result, rather than a score of zero.
Perhaps because they eliminated the fainter bands â the ones most likely to be erroneous â their estimate of specificity for BioMedomics, the one test that was evaluated by both teams, was more than 99 percent, compared with the San Francisco teamâs estimate of 87 percent.
Other experts were skeptical of the scoring approach, however. âThatâs not really a method that would give you a real quantitation,â said Florian Krammer of the Icahn School of Medicine at Mount Sinai in New York.
Dr. Krammer has developed a two-step Elisa test that he said has 100 percent specificity and delivers a measure of the quantity of IgM and IgG antibodies a person has. Scoring a rapid testâs bands might offer some data for a scientific study, he said, âbut I would not make any decisions based on that.â
Dr. Krammer said false positives are less of an issue for assessing how widely the virus has spread in the population. If a test has a known false-positive rate, scientists can factor that into their calculations, he said.
But false positives become dangerous when making policy and personal decisions about who can go back to work. âYou donât want anybody back to work who has a false positive â thatâs the last thing you want to do,â Dr. Krammer said.
Scanwell Health, a Los Angeles-based start-up, has ordered millions of test kits from Innovita, a Chinese manufacturer, and has applied to the Food and Drug Administration to market the tests for at-home use.
In the new study, the Innovita test detected antibodies in 83 percent of infected people and yielded a false-positive rate of 4 percent.
Dr. Jack Jeng, chief medical officer of Scanwell Health, said the study looked at an earlier version of Innovitaâs test and not the ânewer, improved versionâ his company had ordered. âIt will be interesting to see how it performs,â he said.
Dr. Marson and his colleagues have acquired tests from nearly 100 manufacturers, and plan to continue comparing them. The scientists also hope to expand their sample set to include people who were mildly ill or did not feel ill at all, and to stratify their data by age and the presence of chronic conditions.
âThis is just the beginning,â Dr. Marson said. âOur goal would be to keep going till we feel thereâs adequate supply in the market.â
[Apoorva Mandavilli](https://www.nytimes.com/by/apoorva-mandavilli) is a reporter focusing on science and global health. She is the 2019 winner of the Victor Cohn Prize for Excellence in Medical Science Reporting.
A version of this article appears in print on April 26, 2020, Section A, Page 6 of the New York edition with the headline: False Positives: 11 of 14 Antibody Tests Are Unreliable, Researchers Find. [Order Reprints](https://nytimes.wrightsmedia.com/) \| [Todayâs Paper](https://www.nytimes.com/section/todayspaper) \| [Subscribe](https://www.nytimes.com/subscriptions/Multiproduct/lp8HYKU.html?campaignId=48JQY)
## Related Content
[The Covid-19 Pandemic](https://www.nytimes.com/news-event/coronavirus)
- 
Callaghan O'Hare for The New York Times
- 
Eric Lee/The New York Times
- Tierney L. Cross/The New York Times
[More in Health](https://www.nytimes.com/section/health)
- 
Hesslefors/ullstein bild, via Getty Images
- 
Federica Bordoni
- 
Kristian Thacker for The New York Times
- 
Kent J. Edwards for The New York Times
Editorsâ Picks
- 
Warrick Page/HBO Max
- 
Illustration by Tomi Um
Trending in The Times
- 
John McConnico for The New York Times
- 
Don Hogan Charles/The New York Times
- 
Illustration by Sam Whitney/The New York Times
- 
- 
An Chen
- 
Lindsey Whitaker
- 
Philip Cheung for The New York Times
- 
Matteo Prandoni/BFA.com
- 
Artu Nepomuceno
- 
Devin Oktar Yalkin for The New York Times
Advertisement
[SKIP ADVERTISEMENT](https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html#after-bottom) |
| Shard | 84 (laksa) |
| Root Hash | 4566504020376537684 |
| Unparsed URL | com,nytimes!www,/2020/04/24/health/coronavirus-antibody-tests.html s443 |