🕷️ Crawler Inspector

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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 127 (from laksa049)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa127.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.kqed.org/news/11972313/negative-covid-test-incubation-period\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.kqed.org/news/11972313/negative-covid-test-incubation-period\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.kqed.org\/news\/11972313\/negative-covid-test-incubation-period","crawl_time":1775540121,"first_indexed_time":1705020030,"http_code":200,"src_unparsed":"org,kqed!www,\/news\/11972313\/negative-covid-test-incubation-period s443","src_root_hash":"17348708998684895127","history_drop_reason":null,"meta_title":"Why Your Negative COVID Test Might Be Less Reliable | KQED","meta_descriptions":["COVID-19's shortened incubation period can lead to false negatives on test done too early. Learn why your initial negative result may not be accurate."],"attrs_boilerpipe_text":"Jan 11, 2024\nUpdated May 20, 2025\nFailed to save article\nPlease try again\nA whole host of winter respiratory viruses is circulating\nin the first weeks of 2024 — which means you probably know several people who are sick right now. And for a fourth January running, we\nstill\nhave to worry about COVID-19.\nAt this stage in the pandemic, worrying that your sore throat, cough or congestion might, in fact, be COVID-19 is a natural thought, especially as\nthe Bay Area is experiencing another wave of infections fueled by the new JN.1 strain\n.\nJump straight to:\nMy first COVID-19 test was negative. What do I do now?\nBut while testing negative on an at-home antigen test can bring some relief, unfortunately, you may no longer be able to trust that initial result in the way you could earlier in the pandemic.\nKeep reading for what you need to know about COVID-19 incubation periods in 2024, why an early negative test could be a false result, and what to do if you’re caught in a “Wait, so do I have COVID or not?” testing limbo.\nIt could take more time to test positive for COVID-19 than in years past\nSome medical experts say they’ve noticed that at this stage of the pandemic, it’s often taking much longer for people to get a positive test result on an at-home COVID-19 antigen test. In other words, they’re observing that people with COVID-19 symptoms are taking an antigen test and getting a negative result — only to get a positive result on a different test several days later.\nThis means that many people could wrongly assume they don’t have COVID-19 after that first negative test and then inadvertently spread the virus to friends and family.\nDr. Peter Chin-Hong, an infectious disease expert at UCSF, said he and his colleagues are now “seeing people take longer to get a positive test” even though they have COVID-19 symptoms.\nDr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California, told the\nLos Angeles Times\nthat she’s also noticed this delay — and that a patient might not get a positive test result up until the fourth day after the start of their symptoms.\nBut there’s a confusing additional aspect to this too: “Paradoxically,” said Chin-Hong, incubation times for the virus have gotten shorter throughout the pandemic. This means people have tested positive for COVID-19 more quickly than in 2020, when the average incubation period was five days because the incubation period has changed with each new variant. Chin-Hong’s advice in the last year has been that if you’re having COVID-19 symptoms, it now makes sense to take a test as early as two days after exposure.\nSo how do shorter incubation times square with this newly observed delay on positive COVID-19 tests?\nYour COVID-19 symptoms might be starting earlier\nRight now, experts aren’t 100% sure why antigen tests are taking longer to return a positive COVID-19 result. But Chin-Hong said that the hypothesis that makes sense to him is less about the efficacy of the antigen tests themselves and way more about how much quicker someone with COVID-19 might develop symptoms in 2024 than they would have done in 2020.\nAs a reminder, those symptoms are the sign that your body’s immune system is mounting a response to an invading virus — and back at the start of the pandemic, by the time you developed COVID-19 symptoms and took a test it would probably already be positive, Chin-Hong said.\nBut at this stage of the pandemic, most of us now have “a lot of immune experience” with COVID-19, Chin-Hong said — and the average person’s immune system is increasingly “on guard” and “activated more than in 2020,” he said. So when your body detects a burgeoning coronavirus infection now, “your whole immune system just gets agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet,” Chin-Hong said.\nDr. Abraar Karan, an infectious disease physician and researcher at Stanford University, also put it this way for NPR: “With our immune systems primed,\nthe body’s response [now] comes much more quickly than it would have back in 2020\nwhen SARS-CoV-2 was a novel pathogen.”\nAnd because many of us take a COVID-19 test when we\nstart\nto feel sick, we might be testing way too early at that time for an at-home antigen kit to successfully detect enough virus inside us. This mismatch between when your symptoms start and when you’ve enough virus present in your body to result in a positive COVID-19 test “was started to be observed in early omicron, but I think it just seems more accentuated now,” Chin-Hong said.\nHowever, Hudson of Kaiser Permanente Southern California told the\nL.A. Times\nthat for her, this delay in positive tests\nmight be attributable to people’s accumulated immunity from COVID-19\n over the years — either from getting infected or getting vaccinated.\n“It’s actually pushing back the time that people’s COVID tests are coming up positive,” Hudson\nsaid\n.\nThe bottom line is: If you’re testing because you’ve started feeling unwell, it’s unwise to assume in 2024 that a negative result automatically means you don’t have COVID-19, because you might just be testing too early.\nSo … what should I do if my first COVID-19 test is negative?\nExperiencing the onset of symptoms that feel like COVID-19 is unpleasant and worrying enough. And now, this new possible delay around even knowing if you have COVID-19 adds another element of frustration and uncertainty to what’s already a stressful situation. Even if you’ve been able to\nfind free COVID-19 tests being given away or by order from the U.S. government via USPS\n, one COVID-19 scare in a family can run through that stockpile pretty fast — and the cost of purchasing new COVID-19 antigen kits can really add up.\nIf you’re in the limbo of not knowing whether you actually have COVID-19 yet, here’s what to do:\nIf your first test is negative for COVID-19, test again later\nIf you have symptoms but have tested negative, don’t assume it means you’re COVID-free.\nThe CDC recommends that you take another antigen test 48 hours later\n and then test again after another 48 hours.\nChin-Hong advises that you can also\nseek out a PCR test\n, which is more sensitive.\nWhile you’re unsure, play it safe \nIf you have symptoms and don’t know why yet for sure, stay home as much as you can. If you truly can’t stay indoors and away from others, wear a well-fitted mask to protect your community and\ntry to ensure you’re in well-ventilated spaces.\nBe especially careful not to spread any virus around folks who are at higher risk for serious illness or hospitalization from COVID-19, which includes older people, immunocompromised and disabled people.\nRemember: Just because it’s not COVID-19 doesn’t mean you’re not still sick\nEven if you turn out not to have COVID-19 after several days of testing but you’re still experiencing symptoms, you might still be infected with one of\nthe other highly infectious winter respiratory viruses out there like flu, RSV or a bad cold.\nAnd if you’re sick, you could easily infect your friends, family or colleagues with whatever you’re suffering from.\nGive yourself permission not to trust a friend’s negative test, too\nWhat if it’s a friend who’s experiencing COVID-19 symptoms, and they’re insisting that they’re safe to meet with you because “they took a test and it’s negative”?\nKnowing what you know — that it can sometimes take folks longer to get a positive COVID-19 test in 2024 — you should feel free to compassionately tell your friend that while you trust\nthem\n, you can’t trust an early negative test right now. There’s a good chance that they have no idea that positive tests can be increasingly delayed and will be relieved to know that by staying home, they haven’t accidentally spread an infectious disease to you or other loved ones.\nAnd if they disagree and insist they’re still safe to meet up? You should feel free to decline, even if it feels awkward.\nRemember, it’s not weird to not want to get COVID-19.\nStock up on free COVID-19 tests …\nFinding a quick, free COVID-19 test — whether an at-home antigen test or a PCR test — has gotten progressively harder at this stage of the pandemic as more sites and services have shuttered. The federal government has, at least, restarted its\nfree at-home COVID-test-ordering service\nthrough USPS, meaning you can once again order another four free antigen tests to be delivered to your door for a future time.\nRead more about where to find free or low-cost COVID-19 tests this winter.\n… but make sure your COVID-19 tests haven’t expired\nMany of the COVID-19 tests being made available right now (\nfor example, at your local public library\n) may be approaching their expiration date if they haven’t already passed it. And an expired test could give you an unreliable result.\nYou can check the FDA’s list of antigen test types\nto see\nwhether the box you’re holding has had its shelf life extended\nby the manufacturer. The FDA said that if a test’s shelf life has been extended, it’s because the manufacturer has given the agency enough “data showing that the shelf-life is longer than was known when the test was first authorized.” (In other words, it’s still OK to use that test.)\nTell us: What else do you need information about?\nAt KQED News, we know that it can sometimes be hard to track down the answers to navigate life in the Bay Area. We’ve published\nclear, practical explainers and guides about COVID-19\n,\nhow to cope with intense winter weather\n, and\nhow to exercise your right to protest safely\n.\nSo tell us: What do you need to know more about? Tell us, and you could see your question answered online or on social media. What you submit will make our reporting stronger and help us decide what to cover here on our site and on KQED Public Radio, too.","attrs_markdown":"- [Skip to Nav](https:\/\/www.kqed.org\/news\/11972313\/negative-covid-test-incubation-period#navBar)\n- [Skip to Main](https:\/\/www.kqed.org\/news\/11972313\/negative-covid-test-incubation-period#main-content)\n- [Skip to Footer](https:\/\/www.kqed.org\/news\/11972313\/negative-covid-test-incubation-period#footer)\n\n![Kqed Logo](https:\/\/cdn.kqed.org\/wp-content\/uploads\/sites\/83\/2024\/12\/YearEnd-KQED-logo-white-196x60@2x.png)\n\n## Last call: 2x your gift\nOur funding has been cut, but we won’t be muted. Right now, Buck & Carolyn Hall are matching all donations up to \\$50,000. Make your tax-deductible donation before midnight on December 31 and make twice the impact for our community.\n\n[Double My Gift](https:\/\/donate.kqed.org\/eoy25?ms=W2512WKDXXXX02)\n\n![](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/10\/YearEnd-2025-image-604x265@2x.jpg)\n\n[Become a KQED Sponsor](https:\/\/www.kqed.org\/support\/sponsorship)\n\nSign In\n\n- [Saved Articles](https:\/\/www.kqed.org\/account\/saved-articles)\n- [Account](https:\/\/www.kqed.org\/account)\n- [Newsletters](https:\/\/www.kqed.org\/newsletters)\n- Sign Out\n\n[Donate](https:\/\/donate.kqed.org\/givetoday)\n\n[Search](https:\/\/www.kqed.org\/search)\n\nNews\n\n- [Politics](https:\/\/www.kqed.org\/politics)\n- [Arts & Culture](https:\/\/www.kqed.org\/arts)\n- [Science](https:\/\/www.kqed.org\/science)\n- [Food](https:\/\/www.kqed.org\/food)\n- [Education](https:\/\/www.kqed.org\/educationnews)\n- [Housing](https:\/\/www.kqed.org\/housing)\n- [Criminal Justice](https:\/\/www.kqed.org\/criminaljustice)\n- [Immigration](https:\/\/www.kqed.org\/immigration)\n\n[![](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/06\/Nav-News-Newsletter@2x.png) News Daily Newsletter Stay on top of what’s happening in the Bay Area with essential Bay Area news stories, sent to your inbox every weekday.](https:\/\/www.kqed.org\/newsletters\/news-daily)\n\nNews\n\n- [Politics](https:\/\/www.kqed.org\/politics)\n- [Arts & Culture](https:\/\/www.kqed.org\/arts)\n- [Science](https:\/\/www.kqed.org\/science)\n- [Food](https:\/\/www.kqed.org\/food)\n\n- [Education](https:\/\/www.kqed.org\/educationnews)\n- [Housing](https:\/\/www.kqed.org\/housing)\n- [Criminal Justice](https:\/\/www.kqed.org\/criminaljustice)\n- [Immigration](https:\/\/www.kqed.org\/immigration)\n\nPodcasts & Radio\n\n- [KQED Podcasts & Shows](https:\/\/www.kqed.org\/podcasts)\n- [Listen to Live Radio](https:\/\/www.kqed.org\/radio)\n- [Radio Schedule](https:\/\/www.kqed.org\/radio\/schedule)\n- [KQED Forum](https:\/\/www.kqed.org\/forum)\n- [Political Breakdown](https:\/\/www.kqed.org\/podcasts\/politicalbreakdown)\n- [Bay Curious](https:\/\/www.kqed.org\/podcasts\/baycurious)\n\n[![](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/11\/Nav-PodcastsRadio-TheBay@2x.png) The Bay Bay Area-raised host Ericka Cruz Guevarra brings you context and analysis to make sense of the news. 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Episodes drop Monday, Wednesday, and Friday.](https:\/\/www.kqed.org\/podcasts\/thebay)\n\n[![Emma’s Must-Sees](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/10\/Nav-Video-TV-Emmas-Must-Sees@2x.jpg)Emma’s Must-Sees See TV Programming Manager Emma Casley’s recommendations from this month’s KQED 9, PLUS and Passport schedules.](https:\/\/www.kqed.org\/mustsees)\n\n[![Videos from KQED Live](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2024\/05\/Nav-Events-Past@2x.jpg)Videos from KQED Live Watch recordings of recent KQED Live events.](https:\/\/www.kqed.org\/events\/archive\/recent)\n\n[![Donor-Advised Funds](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2024\/05\/Nav-Support-Legacy-Challenge@2x.jpg)Donor-Advised Funds Support KQED by using your donor-advised fund to make a charitable gift.](https:\/\/www.kqed.org\/support\/donor-advised-funds)\n\nupper waypoint\n\n![An array of at-home COVID-19 test boxes.](https:\/\/cdn.kqed.org\/wp-content\/uploads\/sites\/10\/2024\/01\/240111-AT-HOME-COVID-TEST-GETTY-MB-KQED-1920x1281.jpg)\n\nBoxes of BinaxNow a COVID-19 at-home test on Aug. 13, 2022.\n\n(Photo illustration by Michael Bocchieri\/Getty Images)\n\n[News](https:\/\/www.kqed.org\/)\n\n1. [Home](https:\/\/www.kqed.org\/)\n   \/\n2. [News](https:\/\/www.kqed.org\/news\/category\/news)\n# The Truth Behind Negative COVID Tests and False Results\n\n[News](https:\/\/www.kqed.org\/)\n\n1. [Home](https:\/\/www.kqed.org\/)\n   \/\n2. [News](https:\/\/www.kqed.org\/news\/category\/news)\n# The Truth Behind Negative COVID Tests and False Results\n\n[Carly Severn](https:\/\/www.kqed.org\/author\/carlysevern)\n\nJan 11, 2024\n\nUpdated May 20, 2025\n\nSave Article\n\nFailed to save article\n\nPlease try again\n\n- [Email](mailto:?subject=Check%20out%20this%20article%20from%20KQED&body=https%3A%2F%2Fwww.kqed.org%2Fnews%2F11972313%2Fnegative-covid-test-incubation-period)\n\n[A whole host of winter respiratory viruses is circulating](https:\/\/www.kqed.org\/news\/11968709\/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) in the first weeks of 2024 — which means you probably know several people who are sick right now. And for a fourth January running, we *still* have to worry about COVID-19.\n\nAt this stage in the pandemic, worrying that your sore throat, cough or congestion might, in fact, be COVID-19 is a natural thought, especially as [the Bay Area is experiencing another wave of infections fueled by the new JN.1 strain](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know).\n\n- **Jump straight to: [My first COVID-19 test was negative. What do I do now?](https:\/\/www.kqed.org\/news\/11972313\/negative-covid-test-incubation-period#covidtestincubation)**\n\nBut while testing negative on an at-home antigen test can bring some relief, unfortunately, you may no longer be able to trust that initial result in the way you could earlier in the pandemic.\n\n[COVID Is Still With Us](https:\/\/www.kqed.org\/news\/11967946\/covid-ventilation-guide-indoors-windows)\n\n[![An illustration shows a pair of hands holding a plate with silverware over a table. Wind rushes in and out of two open windows, and bright pink COVID symbols waft in the wind.](https:\/\/cdn.kqed.org\/wp-content\/uploads\/sites\/10\/2023\/11\/IMG_0507-1020x659.jpg)How to Improve Indoor Airflow at Your Holiday Gathering](https:\/\/www.kqed.org\/news\/11967946\/covid-ventilation-guide-indoors-windows \"How to Improve Indoor Airflow at Your Holiday Gathering\")\n\n[![Three vaccine bottles - labeled 'RSV,' 'COVID-19' and 'Flu' sit next to a syringe and stethoscope on a medical table.](https:\/\/ww2.kqed.org\/app\/uploads\/sites\/10\/2023\/11\/GettyImages-1447896208-1020x680.jpg)Cold, Flu, or RSV? How to Identify Your Illness](https:\/\/www.kqed.org\/news\/11968709\/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms \"Cold, Flu, or RSV? How to Identify Your Illness\")\n\n[![A hand holds two bright orange boxes that read \"COVID-19 Antigen Rapid Test\" on them.](https:\/\/cdn.kqed.org\/wp-content\/uploads\/sites\/10\/2023\/12\/231215-COVID-TESTS-GETTY-AW-KQED-1020x680.jpg)How to Get Free COVID Tests from Your Local Library](https:\/\/www.kqed.org\/news\/11970001\/free-covid-tests-near-me-public-library \"How to Get Free COVID Tests from Your Local Library\")\n\n[![A white box with blue and red coloring on the left side that says \"Paxlovid.\"](https:\/\/ww2.kqed.org\/app\/uploads\/sites\/10\/2023\/11\/GettyImages-1387450682-1020x680.jpg)Accessing Free Paxlovid in California Amid Policy Changes](https:\/\/www.kqed.org\/news\/11966797\/paxlovid-free-eligibility-california-2023 \"Accessing Free Paxlovid in California Amid Policy Changes\")\n\nKeep reading for what you need to know about COVID-19 incubation periods in 2024, why an early negative test could be a false result, and what to do if you’re caught in a “Wait, so do I have COVID or not?” testing limbo.\n\n## It could take more time to test positive for COVID-19 than in years past\nSome medical experts say they’ve noticed that at this stage of the pandemic, it’s often taking much longer for people to get a positive test result on an at-home COVID-19 antigen test. In other words, they’re observing that people with COVID-19 symptoms are taking an antigen test and getting a negative result — only to get a positive result on a different test several days later.\n\nThis means that many people could wrongly assume they don’t have COVID-19 after that first negative test and then inadvertently spread the virus to friends and family.\n\nDr. Peter Chin-Hong, an infectious disease expert at UCSF, said he and his colleagues are now “seeing people take longer to get a positive test” even though they have COVID-19 symptoms. [Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California, told the *Los Angeles Times*](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections) that she’s also noticed this delay — and that a patient might not get a positive test result up until the fourth day after the start of their symptoms.\n\nBut there’s a confusing additional aspect to this too: “Paradoxically,” said Chin-Hong, incubation times for the virus have gotten shorter throughout the pandemic. This means people have tested positive for COVID-19 more quickly than in 2020, when the average incubation period was five days because the incubation period has changed with each new variant. Chin-Hong’s advice in the last year has been that if you’re having COVID-19 symptoms, it now makes sense to take a test as early as two days after exposure.\n\nSo how do shorter incubation times square with this newly observed delay on positive COVID-19 tests?\n\n## Your COVID-19 symptoms might be starting earlier\nRight now, experts aren’t 100% sure why antigen tests are taking longer to return a positive COVID-19 result. But Chin-Hong said that the hypothesis that makes sense to him is less about the efficacy of the antigen tests themselves and way more about how much quicker someone with COVID-19 might develop symptoms in 2024 than they would have done in 2020.\n\nAs a reminder, those symptoms are the sign that your body’s immune system is mounting a response to an invading virus — and back at the start of the pandemic, by the time you developed COVID-19 symptoms and took a test it would probably already be positive, Chin-Hong said.\n\nBut at this stage of the pandemic, most of us now have “a lot of immune experience” with COVID-19, Chin-Hong said — and the average person’s immune system is increasingly “on guard” and “activated more than in 2020,” he said. So when your body detects a burgeoning coronavirus infection now, “your whole immune system just gets agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet,” Chin-Hong said.\n\nDr. Abraar Karan, an infectious disease physician and researcher at Stanford University, also put it this way for NPR: “With our immune systems primed, [the body’s response \\[now\\] comes much more quickly than it would have back in 2020](https:\/\/www.npr.org\/sections\/goatsandsoda\/2024\/01\/07\/1222847727\/coronavirus-faq-my-partner-roommate-kid-got-covid-and-i-didnt-how-come) when SARS-CoV-2 was a novel pathogen.”\n\nAnd because many of us take a COVID-19 test when we *start* to feel sick, we might be testing way too early at that time for an at-home antigen kit to successfully detect enough virus inside us. This mismatch between when your symptoms start and when you’ve enough virus present in your body to result in a positive COVID-19 test “was started to be observed in early omicron, but I think it just seems more accentuated now,” Chin-Hong said.\n\nHowever, Hudson of Kaiser Permanente Southern California told the *L.A. Times* that for her, this delay in positive tests [might be attributable to people’s accumulated immunity from COVID-19](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections) over the years — either from getting infected or getting vaccinated.\n\n[“It’s actually pushing back the time that people’s COVID tests are coming up positive,” Hudson](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections) [said](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections)[.](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections)\n\nThe bottom line is: If you’re testing because you’ve started feeling unwell, it’s unwise to assume in 2024 that a negative result automatically means you don’t have COVID-19, because you might just be testing too early.\n\n[Become a KQED Sponsor](https:\/\/www.kqed.org\/support\/sponsorship)\n\n## So … what should I do if my first COVID-19 test is negative?\nExperiencing the onset of symptoms that feel like COVID-19 is unpleasant and worrying enough. And now, this new possible delay around even knowing if you have COVID-19 adds another element of frustration and uncertainty to what’s already a stressful situation. Even if you’ve been able to [find free COVID-19 tests being given away or by order from the U.S. government via USPS](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), one COVID-19 scare in a family can run through that stockpile pretty fast — and the cost of purchasing new COVID-19 antigen kits can really add up.\n\nIf you’re in the limbo of not knowing whether you actually have COVID-19 yet, here’s what to do:\n\n**If your first test is negative for COVID-19, test again later**\n\nIf you have symptoms but have tested negative, don’t assume it means you’re COVID-free. [The CDC recommends that you take another antigen test 48 hours later](https:\/\/www.cdc.gov\/coronavirus\/2019-ncov\/symptoms-testing\/testing.html) and then test again after another 48 hours.\n\nChin-Hong advises that you can also [seek out a PCR test](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), which is more sensitive.\n\n**While you’re unsure, play it safe**\n\nIf you have symptoms and don’t know why yet for sure, stay home as much as you can. If you truly can’t stay indoors and away from others, wear a well-fitted mask to protect your community and [try to ensure you’re in well-ventilated spaces.](https:\/\/www.kqed.org\/news\/11967946\/covid-ventilation-guide-indoors-windows)\n\nBe especially careful not to spread any virus around folks who are at higher risk for serious illness or hospitalization from COVID-19, which includes older people, immunocompromised and disabled people.\n\n**Remember: Just because it’s not COVID-19 doesn’t mean you’re not still sick**\n\nEven if you turn out not to have COVID-19 after several days of testing but you’re still experiencing symptoms, you might still be infected with one of [the other highly infectious winter respiratory viruses out there like flu, RSV or a bad cold.](https:\/\/www.kqed.org\/news\/11968709\/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) And if you’re sick, you could easily infect your friends, family or colleagues with whatever you’re suffering from.\n\n**Give yourself permission not to trust a friend’s negative test, too**\n\nWhat if it’s a friend who’s experiencing COVID-19 symptoms, and they’re insisting that they’re safe to meet with you because “they took a test and it’s negative”?\n\nKnowing what you know — that it can sometimes take folks longer to get a positive COVID-19 test in 2024 — you should feel free to compassionately tell your friend that while you trust *them*, you can’t trust an early negative test right now. There’s a good chance that they have no idea that positive tests can be increasingly delayed and will be relieved to know that by staying home, they haven’t accidentally spread an infectious disease to you or other loved ones.\n\nAnd if they disagree and insist they’re still safe to meet up? You should feel free to decline, even if it feels awkward. [Remember, it’s not weird to not want to get COVID-19.](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know)\n\n**Stock up on free COVID-19 tests …**\n\nFinding a quick, free COVID-19 test — whether an at-home antigen test or a PCR test — has gotten progressively harder at this stage of the pandemic as more sites and services have shuttered. The federal government has, at least, restarted its [free at-home COVID-test-ordering service](https:\/\/www.covid.gov\/tests) through USPS, meaning you can once again order another four free antigen tests to be delivered to your door for a future time.\n\n[Read more about where to find free or low-cost COVID-19 tests this winter.](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests)\n\n**… but make sure your COVID-19 tests haven’t expired**\n\nMany of the COVID-19 tests being made available right now ([for example, at your local public library](https:\/\/www.kqed.org\/news\/11970001\/free-covid-tests-near-me-public-library)) may be approaching their expiration date if they haven’t already passed it. And an expired test could give you an unreliable result.\n\n[You can check the FDA’s list of antigen test types](https:\/\/www.fda.gov\/medical-devices\/coronavirus-covid-19-and-medical-devices\/home-otc-covid-19-diagnostic-tests#list) to see [whether the box you’re holding has had its shelf life extended](https:\/\/www.fda.gov\/medical-devices\/coronavirus-covid-19-and-medical-devices\/home-otc-covid-19-diagnostic-tests#list) by the manufacturer. The FDA said that if a test’s shelf life has been extended, it’s because the manufacturer has given the agency enough “data showing that the shelf-life is longer than was known when the test was first authorized.” (In other words, it’s still OK to use that test.)\n\n## Tell us: What else do you need information about?\nAt KQED News, we know that it can sometimes be hard to track down the answers to navigate life in the Bay Area. We’ve published [clear, practical explainers and guides about COVID-19](https:\/\/www.kqed.org\/news\/tag\/coronavirus-resources-and-explainers), [how to cope with intense winter weather](https:\/\/www.kqed.org\/news\/11936674\/how-to-prepare-for-this-weeks-atmospheric-river-storm-sandbags-emergency-kits-and-more), and [how to exercise your right to protest safely](https:\/\/www.kqed.org\/news\/11821950\/how-to-safely-attend-a-protest-in-the-bay-area).\n\nSo tell us: What do you need to know more about? Tell us, and you could see your question answered online or on social media. What you submit will make our reporting stronger and help us decide what to cover here on our site and on KQED Public Radio, too.\n\n[Become a KQED Sponsor](https:\/\/www.kqed.org\/support\/sponsorship)\n\n[Become a KQED Sponsor](https:\/\/www.kqed.org\/support\/sponsorship)\n\nCalifornia News\n\n![sanjosespotlight.com](https:\/\/gofetch.imgix.net\/https%3A%2F%2Fdml.market%2Fassets%2Fproperties%2Fsanjosespotlight.com%2Fsjs-footer-v2.png?ixlib=js-2.3.2&fit=max&w=600&h=60&s=4b80f4c4a24e16b3f2e25bdb90dd7620)\n\n![San Jose mayor behind in polls but ahead on prediction markets](https:\/\/gofetch.imgix.net\/https%3A%2F%2Fs3.amazonaws.com%2Fstatic.assets.boss%2Fuploads%2Fcms%2Fd14e26bd-d496-42bf-8c18-266879d39180.jpg?ixlib=js-2.3.2&w=420&h=280&fit=crop&crop=entropy&s=4fd087c1cd4fbc313f205d3b2cefc8dc)\n\nSan Jose mayor behind in polls but ahead on prediction markets\n\nTraditional polling puts San Jose Mayor Matt Mahan toward the back of the pack in the race for California governor. But online gambling markets are betting bigger on his success.\n\ncalifornianews\n\nRead more\n\n![noozhawk.com](https:\/\/gofetch.imgix.net\/https%3A%2F%2Fdml.market%2Fassets%2Fproperties%2Fnoozhawk.com%2FNoozhawk_Web_Transparent.webp?ixlib=js-2.3.2&fit=max&w=600&h=60&s=44d8254834df8289c3dc649a77bd2266)\n\n![Giant Pacific Seahorses, Vulnerable to Extinction, Back at Santa Barbara’s Sea Center](https:\/\/gofetch.imgix.net\/https%3A%2F%2Fs3.amazonaws.com%2Fstatic.assets.boss%2Fuploads%2Fcms%2F960d60f1-e4cd-4719-a59a-518b4f926644.webp?ixlib=js-2.3.2&w=420&h=280&fit=crop&crop=entropy&s=e69d3a47d4e1dc72a60c3483da5a05ec)\n\nGiant Pacific Seahorses, Vulnerable to Extinction, Back at Santa Barbara’s Sea Center\n\nby Julia McHugh, Noozhawk Contributing Writer \\| March 29, 2026 \\| 7:59 pm\n\nRead more\n\n![timesofsandiego.com](https:\/\/gofetch.imgix.net\/https%3A%2F%2Ftimesofsandiego.com%2Fwp-content%2Fuploads%2F2014%2F05%2FTOSD-for-Google-Editors-Picks.png?ixlib=js-2.3.2&fit=max&w=600&h=60&s=0b0f18cfd85661366f6450f6d3575d73)\n\n![Report: Petco Park a \\$1 billion economic engine for San Diego’s economy](https:\/\/gofetch.imgix.net\/https%3A%2F%2Fs3.amazonaws.com%2Fstatic.assets.boss%2Fuploads%2Fcms%2F61bd2092-7f3f-4a3e-8ae8-b116e522d0a9.webp?ixlib=js-2.3.2&w=420&h=280&fit=crop&crop=entropy&s=470c125c72c0ec2bcf70f1df9dfef17b)\n\nReport: Petco Park a \\$1 billion economic engine for San Diego’s economy\n\nAs baseball season begins and the San Diego Padres explore a sale, a new report shows that Petco Park generates nearly \\$1 billion in economic impact for the region and supports 15,000 jobs.\n\ncalifornianews\n\nRead more\n\nlower waypoint\n\n![](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/06\/Newsletter-News-Daily-Mobile-375x272@2x.jpg)\n\nStay on top of what’s happening in the Bay Area\n\nSubscribe to News Daily for essential Bay Area news stories, sent to your inbox every weekday.\n\nTo learn more about how we use your information, please read our [privacy policy](https:\/\/www.kqed.org\/about\/privacy-policy).\n\n## Successfully subscribed.[Browse more newsletters](https:\/\/www.kqed.org\/newsletters)\n\nnext waypoint\n\nDownload the KQED app:\n\n![Download on the App Store](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/07\/apple-app-store-badge@2x.png)\n\n![Get it on Google Play](https:\/\/cdn.kqed.org\/wp-content\/uploads\/2025\/07\/google-play-badge@2x.png)\n\nCopyright © 2026 KQED Inc. 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All Rights Reserved.\n\n[Terms of Service](https:\/\/www.kqed.org\/about\/terms-service)[Privacy Policy](https:\/\/www.kqed.org\/about\/privacy-policy)\n\nLive Radio\n\nClimate One\n\nPlayer sponsored by\n\n![](https:\/\/www.facebook.com\/tr?id=1151600784932979&ev=PageView&noscript=1) ![](https:\/\/www.facebook.com\/tr?id=314319152322771&ev=PageView%0A&noscript=1)\n\n![](https:\/\/www.facebook.com\/tr?id=1559598741433695&ev=PageView&noscript=1)","attrs_readable_markdown":"Jan 11, 2024\n\nUpdated May 20, 2025\n\nFailed to save article\n\nPlease try again\n\n[A whole host of winter respiratory viruses is circulating](https:\/\/www.kqed.org\/news\/11968709\/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) in the first weeks of 2024 — which means you probably know several people who are sick right now. And for a fourth January running, we *still* have to worry about COVID-19.\n\nAt this stage in the pandemic, worrying that your sore throat, cough or congestion might, in fact, be COVID-19 is a natural thought, especially as [the Bay Area is experiencing another wave of infections fueled by the new JN.1 strain](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know).\n\n- **Jump straight to: [My first COVID-19 test was negative. What do I do now?](https:\/\/www.kqed.org\/news\/11972313\/negative-covid-test-incubation-period#covidtestincubation)**\n\nBut while testing negative on an at-home antigen test can bring some relief, unfortunately, you may no longer be able to trust that initial result in the way you could earlier in the pandemic.\n\nKeep reading for what you need to know about COVID-19 incubation periods in 2024, why an early negative test could be a false result, and what to do if you’re caught in a “Wait, so do I have COVID or not?” testing limbo.\n\n## It could take more time to test positive for COVID-19 than in years past\nSome medical experts say they’ve noticed that at this stage of the pandemic, it’s often taking much longer for people to get a positive test result on an at-home COVID-19 antigen test. In other words, they’re observing that people with COVID-19 symptoms are taking an antigen test and getting a negative result — only to get a positive result on a different test several days later.\n\nThis means that many people could wrongly assume they don’t have COVID-19 after that first negative test and then inadvertently spread the virus to friends and family.\n\nDr. Peter Chin-Hong, an infectious disease expert at UCSF, said he and his colleagues are now “seeing people take longer to get a positive test” even though they have COVID-19 symptoms. [Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California, told the *Los Angeles Times*](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections) that she’s also noticed this delay — and that a patient might not get a positive test result up until the fourth day after the start of their symptoms.\n\nBut there’s a confusing additional aspect to this too: “Paradoxically,” said Chin-Hong, incubation times for the virus have gotten shorter throughout the pandemic. This means people have tested positive for COVID-19 more quickly than in 2020, when the average incubation period was five days because the incubation period has changed with each new variant. Chin-Hong’s advice in the last year has been that if you’re having COVID-19 symptoms, it now makes sense to take a test as early as two days after exposure.\n\nSo how do shorter incubation times square with this newly observed delay on positive COVID-19 tests?\n\n## Your COVID-19 symptoms might be starting earlier\nRight now, experts aren’t 100% sure why antigen tests are taking longer to return a positive COVID-19 result. But Chin-Hong said that the hypothesis that makes sense to him is less about the efficacy of the antigen tests themselves and way more about how much quicker someone with COVID-19 might develop symptoms in 2024 than they would have done in 2020.\n\nAs a reminder, those symptoms are the sign that your body’s immune system is mounting a response to an invading virus — and back at the start of the pandemic, by the time you developed COVID-19 symptoms and took a test it would probably already be positive, Chin-Hong said.\n\nBut at this stage of the pandemic, most of us now have “a lot of immune experience” with COVID-19, Chin-Hong said — and the average person’s immune system is increasingly “on guard” and “activated more than in 2020,” he said. So when your body detects a burgeoning coronavirus infection now, “your whole immune system just gets agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet,” Chin-Hong said.\n\nDr. Abraar Karan, an infectious disease physician and researcher at Stanford University, also put it this way for NPR: “With our immune systems primed, [the body’s response \\[now\\] comes much more quickly than it would have back in 2020](https:\/\/www.npr.org\/sections\/goatsandsoda\/2024\/01\/07\/1222847727\/coronavirus-faq-my-partner-roommate-kid-got-covid-and-i-didnt-how-come) when SARS-CoV-2 was a novel pathogen.”\n\nAnd because many of us take a COVID-19 test when we *start* to feel sick, we might be testing way too early at that time for an at-home antigen kit to successfully detect enough virus inside us. This mismatch between when your symptoms start and when you’ve enough virus present in your body to result in a positive COVID-19 test “was started to be observed in early omicron, but I think it just seems more accentuated now,” Chin-Hong said.\n\nHowever, Hudson of Kaiser Permanente Southern California told the *L.A. Times* that for her, this delay in positive tests [might be attributable to people’s accumulated immunity from COVID-19](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections) over the years — either from getting infected or getting vaccinated.\n\n[“It’s actually pushing back the time that people’s COVID tests are coming up positive,” Hudson](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections) [said](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections)[.](https:\/\/www.latimes.com\/california\/story\/2024-01-09\/covid-rising-home-test-taking-longer-discover-infections)\n\nThe bottom line is: If you’re testing because you’ve started feeling unwell, it’s unwise to assume in 2024 that a negative result automatically means you don’t have COVID-19, because you might just be testing too early.\n\n## So … what should I do if my first COVID-19 test is negative?\nExperiencing the onset of symptoms that feel like COVID-19 is unpleasant and worrying enough. And now, this new possible delay around even knowing if you have COVID-19 adds another element of frustration and uncertainty to what’s already a stressful situation. Even if you’ve been able to [find free COVID-19 tests being given away or by order from the U.S. government via USPS](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), one COVID-19 scare in a family can run through that stockpile pretty fast — and the cost of purchasing new COVID-19 antigen kits can really add up.\n\nIf you’re in the limbo of not knowing whether you actually have COVID-19 yet, here’s what to do:\n\n**If your first test is negative for COVID-19, test again later**\n\nIf you have symptoms but have tested negative, don’t assume it means you’re COVID-free. [The CDC recommends that you take another antigen test 48 hours later](https:\/\/www.cdc.gov\/coronavirus\/2019-ncov\/symptoms-testing\/testing.html) and then test again after another 48 hours.\n\nChin-Hong advises that you can also [seek out a PCR test](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), which is more sensitive.\n\n**While you’re unsure, play it safe**\n\nIf you have symptoms and don’t know why yet for sure, stay home as much as you can. If you truly can’t stay indoors and away from others, wear a well-fitted mask to protect your community and [try to ensure you’re in well-ventilated spaces.](https:\/\/www.kqed.org\/news\/11967946\/covid-ventilation-guide-indoors-windows)\n\nBe especially careful not to spread any virus around folks who are at higher risk for serious illness or hospitalization from COVID-19, which includes older people, immunocompromised and disabled people.\n\n**Remember: Just because it’s not COVID-19 doesn’t mean you’re not still sick**\n\nEven if you turn out not to have COVID-19 after several days of testing but you’re still experiencing symptoms, you might still be infected with one of [the other highly infectious winter respiratory viruses out there like flu, RSV or a bad cold.](https:\/\/www.kqed.org\/news\/11968709\/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) And if you’re sick, you could easily infect your friends, family or colleagues with whatever you’re suffering from.\n\n**Give yourself permission not to trust a friend’s negative test, too**\n\nWhat if it’s a friend who’s experiencing COVID-19 symptoms, and they’re insisting that they’re safe to meet with you because “they took a test and it’s negative”?\n\nKnowing what you know — that it can sometimes take folks longer to get a positive COVID-19 test in 2024 — you should feel free to compassionately tell your friend that while you trust *them*, you can’t trust an early negative test right now. There’s a good chance that they have no idea that positive tests can be increasingly delayed and will be relieved to know that by staying home, they haven’t accidentally spread an infectious disease to you or other loved ones.\n\nAnd if they disagree and insist they’re still safe to meet up? You should feel free to decline, even if it feels awkward. [Remember, it’s not weird to not want to get COVID-19.](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know)\n\n**Stock up on free COVID-19 tests …**\n\nFinding a quick, free COVID-19 test — whether an at-home antigen test or a PCR test — has gotten progressively harder at this stage of the pandemic as more sites and services have shuttered. The federal government has, at least, restarted its [free at-home COVID-test-ordering service](https:\/\/www.covid.gov\/tests) through USPS, meaning you can once again order another four free antigen tests to be delivered to your door for a future time.\n\n[Read more about where to find free or low-cost COVID-19 tests this winter.](https:\/\/www.kqed.org\/news\/11957790\/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests)\n\n**… but make sure your COVID-19 tests haven’t expired**\n\nMany of the COVID-19 tests being made available right now ([for example, at your local public library](https:\/\/www.kqed.org\/news\/11970001\/free-covid-tests-near-me-public-library)) may be approaching their expiration date if they haven’t already passed it. And an expired test could give you an unreliable result.\n\n[You can check the FDA’s list of antigen test types](https:\/\/www.fda.gov\/medical-devices\/coronavirus-covid-19-and-medical-devices\/home-otc-covid-19-diagnostic-tests#list) to see [whether the box you’re holding has had its shelf life extended](https:\/\/www.fda.gov\/medical-devices\/coronavirus-covid-19-and-medical-devices\/home-otc-covid-19-diagnostic-tests#list) by the manufacturer. The FDA said that if a test’s shelf life has been extended, it’s because the manufacturer has given the agency enough “data showing that the shelf-life is longer than was known when the test was first authorized.” (In other words, it’s still OK to use that test.)\n\n## Tell us: What else do you need information about?\nAt KQED News, we know that it can sometimes be hard to track down the answers to navigate life in the Bay Area. We’ve published [clear, practical explainers and guides about COVID-19](https:\/\/www.kqed.org\/news\/tag\/coronavirus-resources-and-explainers), [how to cope with intense winter weather](https:\/\/www.kqed.org\/news\/11936674\/how-to-prepare-for-this-weeks-atmospheric-river-storm-sandbags-emergency-kits-and-more), and [how to exercise your right to protest safely](https:\/\/www.kqed.org\/news\/11821950\/how-to-safely-attend-a-protest-in-the-bay-area).\n\nSo tell us: What do you need to know more about? Tell us, and you could see your question answered online or on social media. What you submit will make our reporting stronger and help us decide what to cover here on our site and on KQED Public Radio, too.","meta_canonical":null}

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URL	https://www.kqed.org/news/11972313/negative-covid-test-incubation-period
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Meta Title	Why Your Negative COVID Test Might Be Less Reliable \| KQED
Meta Description	COVID-19's shortened incubation period can lead to false negatives on test done too early. Learn why your initial negative result may not be accurate.
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Boilerpipe Text	Jan 11, 2024 Updated May 20, 2025 Failed to save article Please try again A whole host of winter respiratory viruses is circulating in the first weeks of 2024 — which means you probably know several people who are sick right now. And for a fourth January running, we still have to worry about COVID-19. At this stage in the pandemic, worrying that your sore throat, cough or congestion might, in fact, be COVID-19 is a natural thought, especially as the Bay Area is experiencing another wave of infections fueled by the new JN.1 strain . Jump straight to: My first COVID-19 test was negative. What do I do now? But while testing negative on an at-home antigen test can bring some relief, unfortunately, you may no longer be able to trust that initial result in the way you could earlier in the pandemic. Keep reading for what you need to know about COVID-19 incubation periods in 2024, why an early negative test could be a false result, and what to do if you’re caught in a “Wait, so do I have COVID or not?” testing limbo. It could take more time to test positive for COVID-19 than in years past Some medical experts say they’ve noticed that at this stage of the pandemic, it’s often taking much longer for people to get a positive test result on an at-home COVID-19 antigen test. In other words, they’re observing that people with COVID-19 symptoms are taking an antigen test and getting a negative result — only to get a positive result on a different test several days later. This means that many people could wrongly assume they don’t have COVID-19 after that first negative test and then inadvertently spread the virus to friends and family. Dr. Peter Chin-Hong, an infectious disease expert at UCSF, said he and his colleagues are now “seeing people take longer to get a positive test” even though they have COVID-19 symptoms. Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California, told the Los Angeles Times that she’s also noticed this delay — and that a patient might not get a positive test result up until the fourth day after the start of their symptoms. But there’s a confusing additional aspect to this too: “Paradoxically,” said Chin-Hong, incubation times for the virus have gotten shorter throughout the pandemic. This means people have tested positive for COVID-19 more quickly than in 2020, when the average incubation period was five days because the incubation period has changed with each new variant. Chin-Hong’s advice in the last year has been that if you’re having COVID-19 symptoms, it now makes sense to take a test as early as two days after exposure. So how do shorter incubation times square with this newly observed delay on positive COVID-19 tests? Your COVID-19 symptoms might be starting earlier Right now, experts aren’t 100% sure why antigen tests are taking longer to return a positive COVID-19 result. But Chin-Hong said that the hypothesis that makes sense to him is less about the efficacy of the antigen tests themselves and way more about how much quicker someone with COVID-19 might develop symptoms in 2024 than they would have done in 2020. As a reminder, those symptoms are the sign that your body’s immune system is mounting a response to an invading virus — and back at the start of the pandemic, by the time you developed COVID-19 symptoms and took a test it would probably already be positive, Chin-Hong said. But at this stage of the pandemic, most of us now have “a lot of immune experience” with COVID-19, Chin-Hong said — and the average person’s immune system is increasingly “on guard” and “activated more than in 2020,” he said. So when your body detects a burgeoning coronavirus infection now, “your whole immune system just gets agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet,” Chin-Hong said. Dr. Abraar Karan, an infectious disease physician and researcher at Stanford University, also put it this way for NPR: “With our immune systems primed, the body’s response [now] comes much more quickly than it would have back in 2020 when SARS-CoV-2 was a novel pathogen.” And because many of us take a COVID-19 test when we start to feel sick, we might be testing way too early at that time for an at-home antigen kit to successfully detect enough virus inside us. This mismatch between when your symptoms start and when you’ve enough virus present in your body to result in a positive COVID-19 test “was started to be observed in early omicron, but I think it just seems more accentuated now,” Chin-Hong said. However, Hudson of Kaiser Permanente Southern California told the L.A. Times that for her, this delay in positive tests might be attributable to people’s accumulated immunity from COVID-19 over the years — either from getting infected or getting vaccinated. “It’s actually pushing back the time that people’s COVID tests are coming up positive,” Hudson said . The bottom line is: If you’re testing because you’ve started feeling unwell, it’s unwise to assume in 2024 that a negative result automatically means you don’t have COVID-19, because you might just be testing too early. So … what should I do if my first COVID-19 test is negative? Experiencing the onset of symptoms that feel like COVID-19 is unpleasant and worrying enough. And now, this new possible delay around even knowing if you have COVID-19 adds another element of frustration and uncertainty to what’s already a stressful situation. Even if you’ve been able to find free COVID-19 tests being given away or by order from the U.S. government via USPS , one COVID-19 scare in a family can run through that stockpile pretty fast — and the cost of purchasing new COVID-19 antigen kits can really add up. If you’re in the limbo of not knowing whether you actually have COVID-19 yet, here’s what to do: If your first test is negative for COVID-19, test again later If you have symptoms but have tested negative, don’t assume it means you’re COVID-free. The CDC recommends that you take another antigen test 48 hours later and then test again after another 48 hours. Chin-Hong advises that you can also seek out a PCR test , which is more sensitive. While you’re unsure, play it safe If you have symptoms and don’t know why yet for sure, stay home as much as you can. If you truly can’t stay indoors and away from others, wear a well-fitted mask to protect your community and try to ensure you’re in well-ventilated spaces. Be especially careful not to spread any virus around folks who are at higher risk for serious illness or hospitalization from COVID-19, which includes older people, immunocompromised and disabled people. Remember: Just because it’s not COVID-19 doesn’t mean you’re not still sick Even if you turn out not to have COVID-19 after several days of testing but you’re still experiencing symptoms, you might still be infected with one of the other highly infectious winter respiratory viruses out there like flu, RSV or a bad cold. And if you’re sick, you could easily infect your friends, family or colleagues with whatever you’re suffering from. Give yourself permission not to trust a friend’s negative test, too What if it’s a friend who’s experiencing COVID-19 symptoms, and they’re insisting that they’re safe to meet with you because “they took a test and it’s negative”? Knowing what you know — that it can sometimes take folks longer to get a positive COVID-19 test in 2024 — you should feel free to compassionately tell your friend that while you trust them , you can’t trust an early negative test right now. There’s a good chance that they have no idea that positive tests can be increasingly delayed and will be relieved to know that by staying home, they haven’t accidentally spread an infectious disease to you or other loved ones. And if they disagree and insist they’re still safe to meet up? You should feel free to decline, even if it feels awkward. Remember, it’s not weird to not want to get COVID-19. Stock up on free COVID-19 tests … Finding a quick, free COVID-19 test — whether an at-home antigen test or a PCR test — has gotten progressively harder at this stage of the pandemic as more sites and services have shuttered. The federal government has, at least, restarted its free at-home COVID-test-ordering service through USPS, meaning you can once again order another four free antigen tests to be delivered to your door for a future time. Read more about where to find free or low-cost COVID-19 tests this winter. … but make sure your COVID-19 tests haven’t expired Many of the COVID-19 tests being made available right now ( for example, at your local public library ) may be approaching their expiration date if they haven’t already passed it. And an expired test could give you an unreliable result. You can check the FDA’s list of antigen test types to see whether the box you’re holding has had its shelf life extended by the manufacturer. The FDA said that if a test’s shelf life has been extended, it’s because the manufacturer has given the agency enough “data showing that the shelf-life is longer than was known when the test was first authorized.” (In other words, it’s still OK to use that test.) Tell us: What else do you need information about? At KQED News, we know that it can sometimes be hard to track down the answers to navigate life in the Bay Area. We’ve published clear, practical explainers and guides about COVID-19 , how to cope with intense winter weather , and how to exercise your right to protest safely . So tell us: What do you need to know more about? Tell us, and you could see your question answered online or on social media. What you submit will make our reporting stronger and help us decide what to cover here on our site and on KQED Public Radio, too.
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(Photo illustration by Michael Bocchieri/Getty Images) [News](https://www.kqed.org/) 1. [Home](https://www.kqed.org/) / 2. [News](https://www.kqed.org/news/category/news) # The Truth Behind Negative COVID Tests and False Results [News](https://www.kqed.org/) 1. [Home](https://www.kqed.org/) / 2. [News](https://www.kqed.org/news/category/news) # The Truth Behind Negative COVID Tests and False Results [Carly Severn](https://www.kqed.org/author/carlysevern) Jan 11, 2024 Updated May 20, 2025 Save Article Failed to save article Please try again - [Email](mailto:?subject=Check%20out%20this%20article%20from%20KQED&body=https%3A%2F%2Fwww.kqed.org%2Fnews%2F11972313%2Fnegative-covid-test-incubation-period) [A whole host of winter respiratory viruses is circulating](https://www.kqed.org/news/11968709/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) in the first weeks of 2024 — which means you probably know several people who are sick right now. And for a fourth January running, we still have to worry about COVID-19. At this stage in the pandemic, worrying that your sore throat, cough or congestion might, in fact, be COVID-19 is a natural thought, especially as [the Bay Area is experiencing another wave of infections fueled by the new JN.1 strain](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know). - Jump straight to: [My first COVID-19 test was negative. What do I do now?](https://www.kqed.org/news/11972313/negative-covid-test-incubation-period#covidtestincubation) But while testing negative on an at-home antigen test can bring some relief, unfortunately, you may no longer be able to trust that initial result in the way you could earlier in the pandemic. [COVID Is Still With Us](https://www.kqed.org/news/11967946/covid-ventilation-guide-indoors-windows) [![An illustration shows a pair of hands holding a plate with silverware over a table. Wind rushes in and out of two open windows, and bright pink COVID symbols waft in the wind.](https://cdn.kqed.org/wp-content/uploads/sites/10/2023/11/IMG_0507-1020x659.jpg)How to Improve Indoor Airflow at Your Holiday Gathering](https://www.kqed.org/news/11967946/covid-ventilation-guide-indoors-windows "How to Improve Indoor Airflow at Your Holiday Gathering") [![Three vaccine bottles - labeled 'RSV,' 'COVID-19' and 'Flu' sit next to a syringe and stethoscope on a medical table.](https://ww2.kqed.org/app/uploads/sites/10/2023/11/GettyImages-1447896208-1020x680.jpg)Cold, Flu, or RSV? How to Identify Your Illness](https://www.kqed.org/news/11968709/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms "Cold, Flu, or RSV? How to Identify Your Illness") [![A hand holds two bright orange boxes that read "COVID-19 Antigen Rapid Test" on them.](https://cdn.kqed.org/wp-content/uploads/sites/10/2023/12/231215-COVID-TESTS-GETTY-AW-KQED-1020x680.jpg)How to Get Free COVID Tests from Your Local Library](https://www.kqed.org/news/11970001/free-covid-tests-near-me-public-library "How to Get Free COVID Tests from Your Local Library") [![A white box with blue and red coloring on the left side that says "Paxlovid."](https://ww2.kqed.org/app/uploads/sites/10/2023/11/GettyImages-1387450682-1020x680.jpg)Accessing Free Paxlovid in California Amid Policy Changes](https://www.kqed.org/news/11966797/paxlovid-free-eligibility-california-2023 "Accessing Free Paxlovid in California Amid Policy Changes") Keep reading for what you need to know about COVID-19 incubation periods in 2024, why an early negative test could be a false result, and what to do if you’re caught in a “Wait, so do I have COVID or not?” testing limbo. ## It could take more time to test positive for COVID-19 than in years past Some medical experts say they’ve noticed that at this stage of the pandemic, it’s often taking much longer for people to get a positive test result on an at-home COVID-19 antigen test. In other words, they’re observing that people with COVID-19 symptoms are taking an antigen test and getting a negative result — only to get a positive result on a different test several days later. This means that many people could wrongly assume they don’t have COVID-19 after that first negative test and then inadvertently spread the virus to friends and family. Dr. Peter Chin-Hong, an infectious disease expert at UCSF, said he and his colleagues are now “seeing people take longer to get a positive test” even though they have COVID-19 symptoms. [Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California, told the Los Angeles Times](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) that she’s also noticed this delay — and that a patient might not get a positive test result up until the fourth day after the start of their symptoms. But there’s a confusing additional aspect to this too: “Paradoxically,” said Chin-Hong, incubation times for the virus have gotten shorter throughout the pandemic. This means people have tested positive for COVID-19 more quickly than in 2020, when the average incubation period was five days because the incubation period has changed with each new variant. Chin-Hong’s advice in the last year has been that if you’re having COVID-19 symptoms, it now makes sense to take a test as early as two days after exposure. So how do shorter incubation times square with this newly observed delay on positive COVID-19 tests? ## Your COVID-19 symptoms might be starting earlier Right now, experts aren’t 100% sure why antigen tests are taking longer to return a positive COVID-19 result. But Chin-Hong said that the hypothesis that makes sense to him is less about the efficacy of the antigen tests themselves and way more about how much quicker someone with COVID-19 might develop symptoms in 2024 than they would have done in 2020. As a reminder, those symptoms are the sign that your body’s immune system is mounting a response to an invading virus — and back at the start of the pandemic, by the time you developed COVID-19 symptoms and took a test it would probably already be positive, Chin-Hong said. But at this stage of the pandemic, most of us now have “a lot of immune experience” with COVID-19, Chin-Hong said — and the average person’s immune system is increasingly “on guard” and “activated more than in 2020,” he said. So when your body detects a burgeoning coronavirus infection now, “your whole immune system just gets agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet,” Chin-Hong said. Dr. Abraar Karan, an infectious disease physician and researcher at Stanford University, also put it this way for NPR: “With our immune systems primed, [the body’s response \[now\] comes much more quickly than it would have back in 2020](https://www.npr.org/sections/goatsandsoda/2024/01/07/1222847727/coronavirus-faq-my-partner-roommate-kid-got-covid-and-i-didnt-how-come) when SARS-CoV-2 was a novel pathogen.” And because many of us take a COVID-19 test when we start to feel sick, we might be testing way too early at that time for an at-home antigen kit to successfully detect enough virus inside us. This mismatch between when your symptoms start and when you’ve enough virus present in your body to result in a positive COVID-19 test “was started to be observed in early omicron, but I think it just seems more accentuated now,” Chin-Hong said. However, Hudson of Kaiser Permanente Southern California told the L.A. Times that for her, this delay in positive tests [might be attributable to people’s accumulated immunity from COVID-19](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) over the years — either from getting infected or getting vaccinated. [“It’s actually pushing back the time that people’s COVID tests are coming up positive,” Hudson](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) [said](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections)[.](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) The bottom line is: If you’re testing because you’ve started feeling unwell, it’s unwise to assume in 2024 that a negative result automatically means you don’t have COVID-19, because you might just be testing too early. [Become a KQED Sponsor](https://www.kqed.org/support/sponsorship) ## So … what should I do if my first COVID-19 test is negative? Experiencing the onset of symptoms that feel like COVID-19 is unpleasant and worrying enough. And now, this new possible delay around even knowing if you have COVID-19 adds another element of frustration and uncertainty to what’s already a stressful situation. Even if you’ve been able to [find free COVID-19 tests being given away or by order from the U.S. government via USPS](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), one COVID-19 scare in a family can run through that stockpile pretty fast — and the cost of purchasing new COVID-19 antigen kits can really add up. If you’re in the limbo of not knowing whether you actually have COVID-19 yet, here’s what to do: If your first test is negative for COVID-19, test again later If you have symptoms but have tested negative, don’t assume it means you’re COVID-free. [The CDC recommends that you take another antigen test 48 hours later](https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html) and then test again after another 48 hours. Chin-Hong advises that you can also [seek out a PCR test](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), which is more sensitive. While you’re unsure, play it safe If you have symptoms and don’t know why yet for sure, stay home as much as you can. If you truly can’t stay indoors and away from others, wear a well-fitted mask to protect your community and [try to ensure you’re in well-ventilated spaces.](https://www.kqed.org/news/11967946/covid-ventilation-guide-indoors-windows) Be especially careful not to spread any virus around folks who are at higher risk for serious illness or hospitalization from COVID-19, which includes older people, immunocompromised and disabled people. Remember: Just because it’s not COVID-19 doesn’t mean you’re not still sick Even if you turn out not to have COVID-19 after several days of testing but you’re still experiencing symptoms, you might still be infected with one of [the other highly infectious winter respiratory viruses out there like flu, RSV or a bad cold.](https://www.kqed.org/news/11968709/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) And if you’re sick, you could easily infect your friends, family or colleagues with whatever you’re suffering from. Give yourself permission not to trust a friend’s negative test, too What if it’s a friend who’s experiencing COVID-19 symptoms, and they’re insisting that they’re safe to meet with you because “they took a test and it’s negative”? Knowing what you know — that it can sometimes take folks longer to get a positive COVID-19 test in 2024 — you should feel free to compassionately tell your friend that while you trust them, you can’t trust an early negative test right now. There’s a good chance that they have no idea that positive tests can be increasingly delayed and will be relieved to know that by staying home, they haven’t accidentally spread an infectious disease to you or other loved ones. And if they disagree and insist they’re still safe to meet up? You should feel free to decline, even if it feels awkward. [Remember, it’s not weird to not want to get COVID-19.](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know) Stock up on free COVID-19 tests … Finding a quick, free COVID-19 test — whether an at-home antigen test or a PCR test — has gotten progressively harder at this stage of the pandemic as more sites and services have shuttered. The federal government has, at least, restarted its [free at-home COVID-test-ordering service](https://www.covid.gov/tests) through USPS, meaning you can once again order another four free antigen tests to be delivered to your door for a future time. [Read more about where to find free or low-cost COVID-19 tests this winter.](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests) … but make sure your COVID-19 tests haven’t expired Many of the COVID-19 tests being made available right now ([for example, at your local public library](https://www.kqed.org/news/11970001/free-covid-tests-near-me-public-library)) may be approaching their expiration date if they haven’t already passed it. And an expired test could give you an unreliable result. [You can check the FDA’s list of antigen test types](https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/home-otc-covid-19-diagnostic-tests#list) to see [whether the box you’re holding has had its shelf life extended](https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/home-otc-covid-19-diagnostic-tests#list) by the manufacturer. The FDA said that if a test’s shelf life has been extended, it’s because the manufacturer has given the agency enough “data showing that the shelf-life is longer than was known when the test was first authorized.” (In other words, it’s still OK to use that test.) ## Tell us: What else do you need information about? At KQED News, we know that it can sometimes be hard to track down the answers to navigate life in the Bay Area. We’ve published [clear, practical explainers and guides about COVID-19](https://www.kqed.org/news/tag/coronavirus-resources-and-explainers), [how to cope with intense winter weather](https://www.kqed.org/news/11936674/how-to-prepare-for-this-weeks-atmospheric-river-storm-sandbags-emergency-kits-and-more), and [how to exercise your right to protest safely](https://www.kqed.org/news/11821950/how-to-safely-attend-a-protest-in-the-bay-area). So tell us: What do you need to know more about? Tell us, and you could see your question answered online or on social media. What you submit will make our reporting stronger and help us decide what to cover here on our site and on KQED Public Radio, too. [Become a KQED Sponsor](https://www.kqed.org/support/sponsorship) [Become a KQED Sponsor](https://www.kqed.org/support/sponsorship) California News ![sanjosespotlight.com](https://gofetch.imgix.net/https%3A%2F%2Fdml.market%2Fassets%2Fproperties%2Fsanjosespotlight.com%2Fsjs-footer-v2.png?ixlib=js-2.3.2&fit=max&w=600&h=60&s=4b80f4c4a24e16b3f2e25bdb90dd7620) ![San Jose mayor behind in polls but ahead on prediction markets](https://gofetch.imgix.net/https%3A%2F%2Fs3.amazonaws.com%2Fstatic.assets.boss%2Fuploads%2Fcms%2Fd14e26bd-d496-42bf-8c18-266879d39180.jpg?ixlib=js-2.3.2&w=420&h=280&fit=crop&crop=entropy&s=4fd087c1cd4fbc313f205d3b2cefc8dc) San Jose mayor behind in polls but ahead on prediction markets Traditional polling puts San Jose Mayor Matt Mahan toward the back of the pack in the race for California governor. But online gambling markets are betting bigger on his success. californianews Read more ![noozhawk.com](https://gofetch.imgix.net/https%3A%2F%2Fdml.market%2Fassets%2Fproperties%2Fnoozhawk.com%2FNoozhawk_Web_Transparent.webp?ixlib=js-2.3.2&fit=max&w=600&h=60&s=44d8254834df8289c3dc649a77bd2266) ![Giant Pacific Seahorses, Vulnerable to Extinction, Back at Santa Barbara’s Sea Center](https://gofetch.imgix.net/https%3A%2F%2Fs3.amazonaws.com%2Fstatic.assets.boss%2Fuploads%2Fcms%2F960d60f1-e4cd-4719-a59a-518b4f926644.webp?ixlib=js-2.3.2&w=420&h=280&fit=crop&crop=entropy&s=e69d3a47d4e1dc72a60c3483da5a05ec) Giant Pacific Seahorses, Vulnerable to Extinction, Back at Santa Barbara’s Sea Center by Julia McHugh, Noozhawk Contributing Writer \\| March 29, 2026 \\| 7:59 pm Read more ![timesofsandiego.com](https://gofetch.imgix.net/https%3A%2F%2Ftimesofsandiego.com%2Fwp-content%2Fuploads%2F2014%2F05%2FTOSD-for-Google-Editors-Picks.png?ixlib=js-2.3.2&fit=max&w=600&h=60&s=0b0f18cfd85661366f6450f6d3575d73) ![Report: Petco Park a \$1 billion economic engine for San Diego’s economy](https://gofetch.imgix.net/https%3A%2F%2Fs3.amazonaws.com%2Fstatic.assets.boss%2Fuploads%2Fcms%2F61bd2092-7f3f-4a3e-8ae8-b116e522d0a9.webp?ixlib=js-2.3.2&w=420&h=280&fit=crop&crop=entropy&s=470c125c72c0ec2bcf70f1df9dfef17b) Report: Petco Park a \$1 billion economic engine for San Diego’s economy As baseball season begins and the San Diego Padres explore a sale, a new report shows that Petco Park generates nearly \$1 billion in economic impact for the region and supports 15,000 jobs. californianews Read more lower waypoint ![](https://cdn.kqed.org/wp-content/uploads/2025/06/Newsletter-News-Daily-Mobile-375x272@2x.jpg) Stay on top of what’s happening in the Bay Area Subscribe to News Daily for essential Bay Area news stories, sent to your inbox every weekday. 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Readable Markdown	Jan 11, 2024 Updated May 20, 2025 Failed to save article Please try again [A whole host of winter respiratory viruses is circulating](https://www.kqed.org/news/11968709/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) in the first weeks of 2024 — which means you probably know several people who are sick right now. And for a fourth January running, we still have to worry about COVID-19. At this stage in the pandemic, worrying that your sore throat, cough or congestion might, in fact, be COVID-19 is a natural thought, especially as [the Bay Area is experiencing another wave of infections fueled by the new JN.1 strain](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know). - Jump straight to: [My first COVID-19 test was negative. What do I do now?](https://www.kqed.org/news/11972313/negative-covid-test-incubation-period#covidtestincubation) But while testing negative on an at-home antigen test can bring some relief, unfortunately, you may no longer be able to trust that initial result in the way you could earlier in the pandemic. Keep reading for what you need to know about COVID-19 incubation periods in 2024, why an early negative test could be a false result, and what to do if you’re caught in a “Wait, so do I have COVID or not?” testing limbo. ## It could take more time to test positive for COVID-19 than in years past Some medical experts say they’ve noticed that at this stage of the pandemic, it’s often taking much longer for people to get a positive test result on an at-home COVID-19 antigen test. In other words, they’re observing that people with COVID-19 symptoms are taking an antigen test and getting a negative result — only to get a positive result on a different test several days later. This means that many people could wrongly assume they don’t have COVID-19 after that first negative test and then inadvertently spread the virus to friends and family. Dr. Peter Chin-Hong, an infectious disease expert at UCSF, said he and his colleagues are now “seeing people take longer to get a positive test” even though they have COVID-19 symptoms. [Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California, told the Los Angeles Times](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) that she’s also noticed this delay — and that a patient might not get a positive test result up until the fourth day after the start of their symptoms. But there’s a confusing additional aspect to this too: “Paradoxically,” said Chin-Hong, incubation times for the virus have gotten shorter throughout the pandemic. This means people have tested positive for COVID-19 more quickly than in 2020, when the average incubation period was five days because the incubation period has changed with each new variant. Chin-Hong’s advice in the last year has been that if you’re having COVID-19 symptoms, it now makes sense to take a test as early as two days after exposure. So how do shorter incubation times square with this newly observed delay on positive COVID-19 tests? ## Your COVID-19 symptoms might be starting earlier Right now, experts aren’t 100% sure why antigen tests are taking longer to return a positive COVID-19 result. But Chin-Hong said that the hypothesis that makes sense to him is less about the efficacy of the antigen tests themselves and way more about how much quicker someone with COVID-19 might develop symptoms in 2024 than they would have done in 2020. As a reminder, those symptoms are the sign that your body’s immune system is mounting a response to an invading virus — and back at the start of the pandemic, by the time you developed COVID-19 symptoms and took a test it would probably already be positive, Chin-Hong said. But at this stage of the pandemic, most of us now have “a lot of immune experience” with COVID-19, Chin-Hong said — and the average person’s immune system is increasingly “on guard” and “activated more than in 2020,” he said. So when your body detects a burgeoning coronavirus infection now, “your whole immune system just gets agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet,” Chin-Hong said. Dr. Abraar Karan, an infectious disease physician and researcher at Stanford University, also put it this way for NPR: “With our immune systems primed, [the body’s response \[now\] comes much more quickly than it would have back in 2020](https://www.npr.org/sections/goatsandsoda/2024/01/07/1222847727/coronavirus-faq-my-partner-roommate-kid-got-covid-and-i-didnt-how-come) when SARS-CoV-2 was a novel pathogen.” And because many of us take a COVID-19 test when we start to feel sick, we might be testing way too early at that time for an at-home antigen kit to successfully detect enough virus inside us. This mismatch between when your symptoms start and when you’ve enough virus present in your body to result in a positive COVID-19 test “was started to be observed in early omicron, but I think it just seems more accentuated now,” Chin-Hong said. However, Hudson of Kaiser Permanente Southern California told the L.A. Times that for her, this delay in positive tests [might be attributable to people’s accumulated immunity from COVID-19](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) over the years — either from getting infected or getting vaccinated. [“It’s actually pushing back the time that people’s COVID tests are coming up positive,” Hudson](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) [said](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections)[.](https://www.latimes.com/california/story/2024-01-09/covid-rising-home-test-taking-longer-discover-infections) The bottom line is: If you’re testing because you’ve started feeling unwell, it’s unwise to assume in 2024 that a negative result automatically means you don’t have COVID-19, because you might just be testing too early. ## So … what should I do if my first COVID-19 test is negative? Experiencing the onset of symptoms that feel like COVID-19 is unpleasant and worrying enough. And now, this new possible delay around even knowing if you have COVID-19 adds another element of frustration and uncertainty to what’s already a stressful situation. Even if you’ve been able to [find free COVID-19 tests being given away or by order from the U.S. government via USPS](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), one COVID-19 scare in a family can run through that stockpile pretty fast — and the cost of purchasing new COVID-19 antigen kits can really add up. If you’re in the limbo of not knowing whether you actually have COVID-19 yet, here’s what to do: If your first test is negative for COVID-19, test again later If you have symptoms but have tested negative, don’t assume it means you’re COVID-free. [The CDC recommends that you take another antigen test 48 hours later](https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html) and then test again after another 48 hours. Chin-Hong advises that you can also [seek out a PCR test](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests), which is more sensitive. While you’re unsure, play it safe If you have symptoms and don’t know why yet for sure, stay home as much as you can. If you truly can’t stay indoors and away from others, wear a well-fitted mask to protect your community and [try to ensure you’re in well-ventilated spaces.](https://www.kqed.org/news/11967946/covid-ventilation-guide-indoors-windows) Be especially careful not to spread any virus around folks who are at higher risk for serious illness or hospitalization from COVID-19, which includes older people, immunocompromised and disabled people. Remember: Just because it’s not COVID-19 doesn’t mean you’re not still sick Even if you turn out not to have COVID-19 after several days of testing but you’re still experiencing symptoms, you might still be infected with one of [the other highly infectious winter respiratory viruses out there like flu, RSV or a bad cold.](https://www.kqed.org/news/11968709/cold-flu-or-rsv-how-to-tell-which-virus-you-might-have-from-testing-to-symptoms) And if you’re sick, you could easily infect your friends, family or colleagues with whatever you’re suffering from. Give yourself permission not to trust a friend’s negative test, too What if it’s a friend who’s experiencing COVID-19 symptoms, and they’re insisting that they’re safe to meet with you because “they took a test and it’s negative”? Knowing what you know — that it can sometimes take folks longer to get a positive COVID-19 test in 2024 — you should feel free to compassionately tell your friend that while you trust them, you can’t trust an early negative test right now. There’s a good chance that they have no idea that positive tests can be increasingly delayed and will be relieved to know that by staying home, they haven’t accidentally spread an infectious disease to you or other loved ones. And if they disagree and insist they’re still safe to meet up? You should feel free to decline, even if it feels awkward. [Remember, it’s not weird to not want to get COVID-19.](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know) Stock up on free COVID-19 tests … Finding a quick, free COVID-19 test — whether an at-home antigen test or a PCR test — has gotten progressively harder at this stage of the pandemic as more sites and services have shuttered. The federal government has, at least, restarted its [free at-home COVID-test-ordering service](https://www.covid.gov/tests) through USPS, meaning you can once again order another four free antigen tests to be delivered to your door for a future time. [Read more about where to find free or low-cost COVID-19 tests this winter.](https://www.kqed.org/news/11957790/the-new-covid-eris-variant-and-rising-cases-what-you-need-to-know#freecovidtests) … but make sure your COVID-19 tests haven’t expired Many of the COVID-19 tests being made available right now ([for example, at your local public library](https://www.kqed.org/news/11970001/free-covid-tests-near-me-public-library)) may be approaching their expiration date if they haven’t already passed it. And an expired test could give you an unreliable result. [You can check the FDA’s list of antigen test types](https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/home-otc-covid-19-diagnostic-tests#list) to see [whether the box you’re holding has had its shelf life extended](https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/home-otc-covid-19-diagnostic-tests#list) by the manufacturer. The FDA said that if a test’s shelf life has been extended, it’s because the manufacturer has given the agency enough “data showing that the shelf-life is longer than was known when the test was first authorized.” (In other words, it’s still OK to use that test.) ## Tell us: What else do you need information about? At KQED News, we know that it can sometimes be hard to track down the answers to navigate life in the Bay Area. We’ve published [clear, practical explainers and guides about COVID-19](https://www.kqed.org/news/tag/coronavirus-resources-and-explainers), [how to cope with intense winter weather](https://www.kqed.org/news/11936674/how-to-prepare-for-this-weeks-atmospheric-river-storm-sandbags-emergency-kits-and-more), and [how to exercise your right to protest safely](https://www.kqed.org/news/11821950/how-to-safely-attend-a-protest-in-the-bay-area). So tell us: What do you need to know more about? Tell us, and you could see your question answered online or on social media. What you submit will make our reporting stronger and help us decide what to cover here on our site and on KQED Public Radio, too.
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