🕷️ Crawler Inspector

URL Lookup

Direct Parameter Lookup

Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 110 (from laksa093)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa110.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.ummhealth.org/simply-well/the-difference-between-pcr-and-antigen-covid-19-tests\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.ummhealth.org/simply-well/the-difference-between-pcr-and-antigen-covid-19-tests\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.ummhealth.org\/simply-well\/the-difference-between-pcr-and-antigen-covid-19-tests","crawl_time":1776437525,"first_indexed_time":1736852135,"http_code":200,"src_unparsed":"org,ummhealth!www,\/simply-well\/the-difference-between-pcr-and-antigen-covid-19-tests s443","src_root_hash":"3203128818065089710","history_drop_reason":null,"meta_title":"The Difference Between PCR and Antigen COVID-19 Tests - SimplyWell - UMass Memorial Health","meta_descriptions":["You or someone you know has probably received a COVID-19 test. But do you know which kind of test you got and its strengths and weaknesses?"],"attrs_boilerpipe_text":"At this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests?\nI’m a molecular biologist\n, and since April 2020, I’ve been part of a team\nworking on a National Institutes of Health-funded program called RADx\n that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19. \nTwo major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as \nPCR tests\n \n– and \nantigen tests\n. Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests?\nPCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform.\n \nKarl Mumm via Wikimedia Commons\n, \nCC BY-SA\nLooking for Genetic Evidence\nThe first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva. \nFor PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a\n \npolymerase chain reaction\n. A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase, and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA. \nLaboratory machines \nrepeat these heating and cooling cycles 30 to 40 times\n, doubling the DNA until there are a \nbillion copies of the original piece\n. The amplified sequence contains fluorescent dye that is read by a machine. \nThe amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a \nhighly sensitive and accurate test\n. With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2. \nHowever, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take \nan hour or more from start to finish\n. Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection, and reporting, it can take\nfrom 12 hours to five days for a person to get results back\n. And finally, they aren’t cheap at $100 or more per test.\nRapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests.\n \nLennardywlee via Wikimedia Commons\n, \nCC BY-SA\nAntigen Tests\nRapid, accurate tests are essential\n \nto contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results. \nAntigen tests, the other major type of coronavirus test, while much faster, are less accurate. Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus. \nTo run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that \nhas antibodies specific to SARS-CoV-2 painted on it in a thin line\n. \nJust like antibodies in your body, the ones on the test strip will \nbind to any antigen in the sample\n. If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2. \nAntigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – \neven at home\n. They also produce results quickly, \ntypically in less than 15 minutes\n. Another benefit is that these tests can be relatively inexpensive at \naround $10-$15 per test\n. \nAntigen tests do have some drawbacks. Depending on the situation, they can be \nless accurate than PCR tests\n. When a person is symptomatic or has a lot of virus in their system, \nantigen tests are very accurate\n. However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can \nmiss early cases of COVID-19\n. It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected.\nMore Tests, Better Knowledge\nA few antigen tests are already available over the counter, and on October 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public. \nAt RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used. \nUnderstanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you. \nThis post is republished from\nThe Conversation\nunder a Creative Commons license. Read the\noriginal article\n. Author Nathaniel Hafer, PhD, is a molecular biologist at UMass Chan Medical School, the academic partner of UMass Memorial Health.","attrs_markdown":"[Skip to main content](https:\/\/www.ummhealth.org\/simply-well\/the-difference-between-pcr-and-antigen-covid-19-tests#main-content)\n\n- [Careers](https:\/\/www.ummhealth.org\/careers)\n- [myChart](https:\/\/mychartonline.umassmemorial.org\/MyChart\/Authentication\/Login)\n- [Patients and Visitors](https:\/\/www.ummhealth.org\/patients-visitors)\n- [Health Professionals](https:\/\/www.ummhealth.org\/health-professionals)\n- [Donate](https:\/\/www.ummhealth.org\/giving)\n\nI want to...\n\nChoose here\n\n- [Request Medical Records](https:\/\/www.ummhealth.org\/patients-visitors\/medical-records)\n- [Volunteer](https:\/\/www.ummhealth.org\/giving\/ways-to-give\/volunteer-services)\n- [Explore Careers](https:\/\/www.ummhealth.org\/careers)\n- [Pay My Bill](https:\/\/www.ummhealth.org\/patients-visitors\/pay-bills-online)\n- [Learn about Insurance Plans Accepted](https:\/\/www.ummhealth.org\/patients-visitors\/insurance-information-patients)\n- [Find a Doctor](https:\/\/physicians.umassmemorial.org\/)\n- [Make an Appointment](https:\/\/www.ummhealth.org\/patients-visitors\/make-appointment)\n- [Go to Patients and Visitors](https:\/\/www.ummhealth.org\/patients-visitors)\n- [Explore Mindfulness](https:\/\/www.ummhealth.org\/services-treatments\/center-mindfulness)\n- [Learn about myChart](https:\/\/www.ummhealth.org\/patients-visitors\/mychart)\n- [Go to EpicCare Link](https:\/\/www.ummhealth.org\/health-professionals\/epiccare-link)\n\nOpen translate options\n\nOpen Search\n\n![UMM Logo](https:\/\/www.ummhealth.org\/sites\/default\/files\/ummh_logo_color.png)\n\n[855-UMASS-MD (855-862-7763)](tel:8558627763)\n\n[![Home](https:\/\/www.ummhealth.org\/sites\/default\/files\/ummh_logo_color.png)](https:\/\/www.ummhealth.org\/)\n\nOpen Search\n\n![UMM Logo](https:\/\/www.ummhealth.org\/sites\/default\/files\/ummh_logo_color.png)\n\nThe Clinical Partner of UMass Chan Medical School\n\n- [All Locations](https:\/\/www.ummhealth.org\/locations)\n  \n  Toggle submenu\n  ## All Locations\n  [View all Locations](https:\/\/www.ummhealth.org\/locations)\n  \n  Find a location by type, service, treatment or distance to you.\n  \n  - Our System of Care\n    - [UMass Memorial Medical Center](https:\/\/www.ummhealth.org\/umass-memorial-medical-center)\n    - [Children's Medical Center](https:\/\/www.ummhealth.org\/childrens-medical-center)\n    - [Harrington](https:\/\/www.ummhealth.org\/harrington)\n    - [HealthAlliance-Clinton Hospital](https:\/\/www.ummhealth.org\/healthalliance-clinton-hospital)\n    - [Milford Regional](https:\/\/www.ummhealth.org\/milford-regional\/about-us)\n    - [Community Healthlink](https:\/\/www.ummhealth.org\/community-healthlink\/about-us)\n    - [UMass Memorial Medical Group](https:\/\/www.ummhealth.org\/umass-memorial-medical-group)\n  \n  - Locations by\n    - [Affiliations](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=1425)\n    - [Behavioral Health Services](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=32)\n    - [Corporate Offices](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=1424)\n    - [Emergency Care](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=1421)\n    - [Imaging Centers](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=35)\n    \n    - [Hospital Campuses](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=34)\n    - [Lab Services](https:\/\/www.ummhealth.org\/locations?field_services_target_id_entityreference_filter=11730)\n    - [Outpatient Health Care Centers](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=36)\n    - [Primary Care Offices](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=23)\n    - [Urgent Care Centers](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=24)\n- [Find a Doctor](https:\/\/physicians.umassmemorial.org\/)\n- [Services and Treatments](https:\/\/www.ummhealth.org\/services-treatments)\n  \n  Toggle submenu\n  ### View Alphabetically\n  - [a](https:\/\/www.ummhealth.org\/services-and-treatments?title=1)\n  - [b](https:\/\/www.ummhealth.org\/services-and-treatments?title=2)\n  - [c](https:\/\/www.ummhealth.org\/services-and-treatments?title=3)\n  - [d](https:\/\/www.ummhealth.org\/services-and-treatments?title=4)\n  - [e](https:\/\/www.ummhealth.org\/services-and-treatments?title=5)\n  - [f](https:\/\/www.ummhealth.org\/services-and-treatments?title=6)\n  - [g](https:\/\/www.ummhealth.org\/services-and-treatments?title=7)\n  - [h](https:\/\/www.ummhealth.org\/services-and-treatments?title=8)\n  - [i](https:\/\/www.ummhealth.org\/services-and-treatments?title=9)\n  - j\n  - [k](https:\/\/www.ummhealth.org\/services-and-treatments?title=11)\n  - [l](https:\/\/www.ummhealth.org\/services-and-treatments?title=12)\n  - [m](https:\/\/www.ummhealth.org\/services-and-treatments?title=13)\n  - [n](https:\/\/www.ummhealth.org\/services-and-treatments?title=14)\n  - [o](https:\/\/www.ummhealth.org\/services-and-treatments?title=15)\n  - [p](https:\/\/www.ummhealth.org\/services-and-treatments?title=16)\n  - q\n  - [r](https:\/\/www.ummhealth.org\/services-and-treatments?title=18)\n  - [s](https:\/\/www.ummhealth.org\/services-and-treatments?title=19)\n  - [t](https:\/\/www.ummhealth.org\/services-and-treatments?title=20)\n  - [u](https:\/\/www.ummhealth.org\/services-and-treatments?title=21)\n  - [v](https:\/\/www.ummhealth.org\/services-and-treatments?title=22)\n  - [w](https:\/\/www.ummhealth.org\/services-and-treatments?title=23)\n  - x\n  - [y](https:\/\/www.ummhealth.org\/services-and-treatments?title=25)\n  - z\n  \n  ## Services and Treatments\n  - [View All Services and Treatments](https:\/\/www.ummhealth.org\/services-treatments)\n    - [Urgent Care](https:\/\/www.ummhealth.org\/services-treatments\/emergency-care\/urgent-care)\n    - [General Surgery](https:\/\/www.ummhealth.org\/services-treatments\/surgery\/general-surgery)\n    - [Center for Mindfulness](https:\/\/www.ummhealth.org\/services-treatments\/center-mindfulness)\n    - [Orthopedics](https:\/\/www.ummhealth.org\/services-treatments\/orthopedics)\n    - [Radiology and Imaging](https:\/\/www.ummhealth.org\/services-treatments\/radiology-and-imaging)\n    - [Gastroenterology](https:\/\/www.ummhealth.org\/services-treatments\/gastroenterology)\n    - [Primary Care](https:\/\/www.ummhealth.org\/services-treatments\/primary-care)\n    - [Diabetes](https:\/\/www.ummhealth.org\/services-treatments\/diabetes)\n    - [Heart and Vascular](https:\/\/www.ummhealth.org\/services-treatments\/heart-and-vascular-care)\n    - [Pediatrics](https:\/\/www.ummhealth.org\/services-treatments?field_entities_target_id=19)\n  \n  [Health Library](https:\/\/www.ummhealth.org\/health-library)\n  \n  Your trusted resource for all types of health conditions, providing you the knowledge to make informed decisions about your health.\n  \n  [Simply Well](https:\/\/www.ummhealth.org\/simply-well)\n  \n  Content to help you live healthy and well. Enhancing your lifestyle is part of our relentless pursuit of helping you live a healthy life.\n\nMenu\n\n- [All Locations](https:\/\/www.ummhealth.org\/locations)\n  \n  Toggle submenu\n  ## All Locations\n  [View all Locations](https:\/\/www.ummhealth.org\/locations)\n  \n  Find a location by type, service, treatment or distance to you.\n  \n  - Our System of Care\n    - [UMass Memorial Medical Center](https:\/\/www.ummhealth.org\/umass-memorial-medical-center)\n    - [Children's Medical Center](https:\/\/www.ummhealth.org\/childrens-medical-center)\n    - [Harrington](https:\/\/www.ummhealth.org\/harrington)\n    - [HealthAlliance-Clinton Hospital](https:\/\/www.ummhealth.org\/healthalliance-clinton-hospital)\n    - [Milford Regional](https:\/\/www.ummhealth.org\/milford-regional\/about-us)\n    - [Community Healthlink](https:\/\/www.ummhealth.org\/community-healthlink\/about-us)\n    - [UMass Memorial Medical Group](https:\/\/www.ummhealth.org\/umass-memorial-medical-group)\n  \n  - Locations by\n    - [Affiliations](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=1425)\n    - [Behavioral Health Services](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=32)\n    - [Corporate Offices](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=1424)\n    - [Emergency Care](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=1421)\n    - [Imaging Centers](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=35)\n    \n    - [Hospital Campuses](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=34)\n    - [Lab Services](https:\/\/www.ummhealth.org\/locations?field_services_target_id_entityreference_filter=11730)\n    - [Outpatient Health Care Centers](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=36)\n    - [Primary Care Offices](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=23)\n    - [Urgent Care Centers](https:\/\/www.ummhealth.org\/locations?field_facility_type_target_id=24)\n- [Find a Doctor](https:\/\/physicians.umassmemorial.org\/)\n- [Services and Treatments](https:\/\/www.ummhealth.org\/services-treatments)\n  \n  Toggle submenu\n  ### View Alphabetically\n  - [a](https:\/\/www.ummhealth.org\/services-and-treatments?title=1)\n  - [b](https:\/\/www.ummhealth.org\/services-and-treatments?title=2)\n  - [c](https:\/\/www.ummhealth.org\/services-and-treatments?title=3)\n  - [d](https:\/\/www.ummhealth.org\/services-and-treatments?title=4)\n  - [e](https:\/\/www.ummhealth.org\/services-and-treatments?title=5)\n  - [f](https:\/\/www.ummhealth.org\/services-and-treatments?title=6)\n  - [g](https:\/\/www.ummhealth.org\/services-and-treatments?title=7)\n  - [h](https:\/\/www.ummhealth.org\/services-and-treatments?title=8)\n  - [i](https:\/\/www.ummhealth.org\/services-and-treatments?title=9)\n  - j\n  - [k](https:\/\/www.ummhealth.org\/services-and-treatments?title=11)\n  - [l](https:\/\/www.ummhealth.org\/services-and-treatments?title=12)\n  - [m](https:\/\/www.ummhealth.org\/services-and-treatments?title=13)\n  - [n](https:\/\/www.ummhealth.org\/services-and-treatments?title=14)\n  - [o](https:\/\/www.ummhealth.org\/services-and-treatments?title=15)\n  - [p](https:\/\/www.ummhealth.org\/services-and-treatments?title=16)\n  - q\n  - [r](https:\/\/www.ummhealth.org\/services-and-treatments?title=18)\n  - [s](https:\/\/www.ummhealth.org\/services-and-treatments?title=19)\n  - [t](https:\/\/www.ummhealth.org\/services-and-treatments?title=20)\n  - [u](https:\/\/www.ummhealth.org\/services-and-treatments?title=21)\n  - [v](https:\/\/www.ummhealth.org\/services-and-treatments?title=22)\n  - [w](https:\/\/www.ummhealth.org\/services-and-treatments?title=23)\n  - x\n  - [y](https:\/\/www.ummhealth.org\/services-and-treatments?title=25)\n  - z\n  \n  ## Services and Treatments\n  - [View All Services and Treatments](https:\/\/www.ummhealth.org\/services-treatments)\n    - [Urgent Care](https:\/\/www.ummhealth.org\/services-treatments\/emergency-care\/urgent-care)\n    - [General Surgery](https:\/\/www.ummhealth.org\/services-treatments\/surgery\/general-surgery)\n    - [Center for Mindfulness](https:\/\/www.ummhealth.org\/services-treatments\/center-mindfulness)\n    - [Orthopedics](https:\/\/www.ummhealth.org\/services-treatments\/orthopedics)\n    - [Radiology and Imaging](https:\/\/www.ummhealth.org\/services-treatments\/radiology-and-imaging)\n    - [Gastroenterology](https:\/\/www.ummhealth.org\/services-treatments\/gastroenterology)\n    - [Primary Care](https:\/\/www.ummhealth.org\/services-treatments\/primary-care)\n    - [Diabetes](https:\/\/www.ummhealth.org\/services-treatments\/diabetes)\n    - [Heart and Vascular](https:\/\/www.ummhealth.org\/services-treatments\/heart-and-vascular-care)\n    - [Pediatrics](https:\/\/www.ummhealth.org\/services-treatments?field_entities_target_id=19)\n  \n  [Health Library](https:\/\/www.ummhealth.org\/health-library)\n  \n  Your trusted resource for all types of health conditions, providing you the knowledge to make informed decisions about your health.\n  \n  [Simply Well](https:\/\/www.ummhealth.org\/simply-well)\n  \n  Content to help you live healthy and well. Enhancing your lifestyle is part of our relentless pursuit of helping you live a healthy life.\n\nI want to...\n\nChoose here\n\n- [Request Medical Records](https:\/\/www.ummhealth.org\/patients-visitors\/medical-records)\n- [Volunteer](https:\/\/www.ummhealth.org\/giving\/ways-to-give\/volunteer-services)\n- [Explore Careers](https:\/\/www.ummhealth.org\/careers)\n- [Pay My Bill](https:\/\/www.ummhealth.org\/patients-visitors\/pay-bills-online)\n- [Learn about Insurance Plans Accepted](https:\/\/www.ummhealth.org\/patients-visitors\/insurance-information-patients)\n- [Find a Doctor](https:\/\/physicians.umassmemorial.org\/)\n- [Make an Appointment](https:\/\/www.ummhealth.org\/patients-visitors\/make-appointment)\n- [Go to Patients and Visitors](https:\/\/www.ummhealth.org\/patients-visitors)\n- [Explore Mindfulness](https:\/\/www.ummhealth.org\/services-treatments\/center-mindfulness)\n- [Learn about myChart](https:\/\/www.ummhealth.org\/patients-visitors\/mychart)\n- [Go to EpicCare Link](https:\/\/www.ummhealth.org\/health-professionals\/epiccare-link)\n\n- [Careers](https:\/\/www.ummhealth.org\/careers)\n- [myChart](https:\/\/mychartonline.umassmemorial.org\/MyChart\/Authentication\/Login)\n- [Patients and Visitors](https:\/\/www.ummhealth.org\/patients-visitors)\n- [Health Professionals](https:\/\/www.ummhealth.org\/health-professionals)\n- [Donate](https:\/\/www.ummhealth.org\/giving)\n\nThe Clinical Partner of UMass Chan Medical School\n\n[SIMPLY WELL BLOG](https:\/\/www.ummhealth.org\/simply-well)\n\n[![The Simply Well logo with the text 'Conversations to keep you healthy and well'.](https:\/\/www.ummhealth.org\/sites\/default\/files\/styles\/entity_logo\/public\/2025-01\/Simply_Well_logo_500x114.png.webp?itok=UJWF9gnn)](https:\/\/www.ummhealth.org\/simply-well)\n\n- [Parenting](https:\/\/www.ummhealth.org\/simply-well\/parenting)\n  \n  Toggle submenu\n  - [Infants and Toddlers](https:\/\/www.ummhealth.org\/simply-well\/parenting\/infants-toddlers)\n  - [School Age](https:\/\/www.ummhealth.org\/simply-well\/parenting\/school-age)\n  - [Teen](https:\/\/www.ummhealth.org\/simply-well\/parenting\/teen)\n- [Food and Fitness](https:\/\/www.ummhealth.org\/simply-well\/food-and-fitness)\n  \n  Toggle submenu\n  - [Exercise](https:\/\/www.ummhealth.org\/simply-well\/food-and-fitness\/exercise)\n  - [Healthy Eating](https:\/\/www.ummhealth.org\/simply-well\/food-and-fitness\/healthy-eating)\n  - [Recipes](https:\/\/www.ummhealth.org\/simply-well\/food-and-fitness\/recipes)\n  - [Sports](https:\/\/www.ummhealth.org\/simply-well\/food-and-fitness\/sports)\n- [Prevention and Wellness](https:\/\/www.ummhealth.org\/simply-well\/prevention-and-wellness)\n- [Mind Matters](https:\/\/www.ummhealth.org\/simply-well\/mind-matters)\n  \n  Toggle submenu\n  - [Mental Health](https:\/\/www.ummhealth.org\/simply-well\/mind-matters\/mental-health)\n  - [Mindfulness](https:\/\/www.ummhealth.org\/simply-well\/mind-matters\/mindfulness)\n- [Care and Conditions](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions)\n  \n  Toggle submenu\n  - [Cancer](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/cancer)\n  - [Colorectal](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/colorectal)\n  - [Diabetes](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/diabetes)\n  - [Heart](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/heart)\n  - [Joint Replacement](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/joint-replacement)\n  - [Orthopedics](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/orthopedics)\n  - [Women's Health](https:\/\/www.ummhealth.org\/simply-well\/care-and-conditions\/womens-health)\n- [About Us](https:\/\/www.ummhealth.org\/simply-well\/about-simply-well)\n- [Search](https:\/\/www.ummhealth.org\/)\n  \n  Toggle submenu\n\n1\\.19.22\n\n# The Difference Between PCR and Antigen COVID-19 Tests\n\n![](https:\/\/www.ummhealth.org\/sites\/default\/files\/styles\/header_hero\/public\/featured_images\/COIVD-19-swab-and-vile-resized.jpg.webp?itok=QInrp7wX)\n\n## Breadcrumb\n1. [Home](https:\/\/www.ummhealth.org\/) ›\n2. [Simply Well](https:\/\/www.ummhealth.org\/simply-well)\n\n[Facebook](\"Facebook\")\n\n[X](\"X\")\n\n[Linkedin](\"Linkedin\")\n\n[Email](\"Email\")\n\n[Copy Link](\"Copy Link\")\n\n[Print](\"Print\")\n\nAt this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests?\n\n[**I’m a molecular biologist**](https:\/\/profiles.umassmed.edu\/display\/14945561), and since April 2020, I’ve been part of a team [**working on a National Institutes of Health-funded program called RADx**](https:\/\/www.nih.gov\/research-training\/medical-research-initiatives\/radx) that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19.\n\nTwo major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as [**PCR tests**](https:\/\/www.fda.gov\/consumers\/consumer-updates\/coronavirus-disease-2019-testing-basics)– and [**antigen tests**](https:\/\/theconversation.com\/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977). Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests?\n\n[![A person in a white coat with gloves placing samples into a red laboratory device.](https:\/\/images.theconversation.com\/files\/430518\/original\/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https:\/\/images.theconversation.com\/files\/430518\/original\/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip)\n\nPCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform. [**Karl Mumm via Wikimedia Commons**](https:\/\/commons.wikimedia.org\/wiki\/File:PCR_masina_kasutamine.jpg#\/media\/File:PCR_masina_kasutamine.jpg)**,** [**CC BY-SA**](http:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/)\n## Looking for Genetic Evidence\nThe first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva.\n\nFor PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a[**polymerase chain reaction**](https:\/\/www.genome.gov\/about-genomics\/fact-sheets\/Polymerase-Chain-Reaction-Fact-Sheet). A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase, and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA.\n\nLaboratory machines [**repeat these heating and cooling cycles 30 to 40 times**](https:\/\/www.jove.com\/v\/5056\/pcr-the-polymerase-chain-reaction), doubling the DNA until there are a [**billion copies of the original piece**](https:\/\/www.thermofisher.com\/us\/en\/home\/life-science\/cloning\/cloning-learning-center\/invitrogen-school-of-molecular-biology\/pcr-education\/pcr-reagents-enzymes\/pcr-basics.html). The amplified sequence contains fluorescent dye that is read by a machine.\n\nThe amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a [**highly sensitive and accurate test**](https:\/\/medlineplus.gov\/lab-tests\/pcr-tests\/). With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2.\n\nHowever, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take [**an hour or more from start to finish**](https:\/\/dx.doi.org\/10.1016%2Fj.bdq.2017.05.002). Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection, and reporting, it can take [**from 12 hours to five days for a person to get results back**](https:\/\/my.clevelandclinic.org\/health\/diagnostics\/21462-covid-19-and-pcr-testing). And finally, they aren’t cheap at \\$100 or more per test.\n\n[![Two small white plastic tests with single lines showing negative tests results and a circular depression to place a sample.](https:\/\/images.theconversation.com\/files\/430526\/original\/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https:\/\/images.theconversation.com\/files\/430526\/original\/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip)\n\nRapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests. [**Lennardywlee via Wikimedia Commons**](https:\/\/commons.wikimedia.org\/wiki\/File:COVID-19_rapid_test.jpg#\/media\/File:COVID-19_rapid_test.jpg)**,** [**CC BY-SA**](http:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/)\n## Antigen Tests\n[**Rapid, accurate tests are essential**](https:\/\/theconversation.com\/over-the-counter-rapid-antigen-tests-can-help-slow-the-spread-of-covid-19-heres-how-to-use-them-effectively-166869)to contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results.\n\nAntigen tests, the other major type of coronavirus test, while much faster, are less accurate. Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus.\n\nTo run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that [**has antibodies specific to SARS-CoV-2 painted on it in a thin line**](https:\/\/theconversation.com\/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977).\n\nJust like antibodies in your body, the ones on the test strip will [**bind to any antigen in the sample**](https:\/\/labtestsonline.org\/tests\/covid-19-antigen-test). If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2.\n\nAntigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – [**even at home**](https:\/\/theconversation.com\/rapid-screening-tests-that-prioritize-speed-over-accuracy-could-be-key-to-ending-the-coronavirus-pandemic-143882). They also produce results quickly, [**typically in less than 15 minutes**](https:\/\/theconversation.com\/will-the-new-15-minute-covid-19-test-solve-us-testing-problems-145285). Another benefit is that these tests can be relatively inexpensive at [**around \\$10-\\$15 per test**](https:\/\/www.cvs.com\/shop\/home-health-care\/home-tests\/home-covid-test).\n\nAntigen tests do have some drawbacks. Depending on the situation, they can be [**less accurate than PCR tests**](https:\/\/doi.org\/10.1093\/infdis\/jiab337). When a person is symptomatic or has a lot of virus in their system, [**antigen tests are very accurate**](https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC7799021\/). However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can [**miss early cases of COVID-19**](https:\/\/doi.org\/10.1038\/d41586-021-00332-4). It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected.\n\n## More Tests, Better Knowledge\nA few antigen tests are already available over the counter, and on October 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public.\n\nAt RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used.\n\nUnderstanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you.\n\nThis post is republished from [**The Conversation**](https:\/\/theconversation.com\/us) under a Creative Commons license. Read the [**original article**](https:\/\/theconversation.com\/whats-the-difference-between-a-pcr-and-antigen-covid-19-test-a-molecular-biologist-explains-170917). Author Nathaniel Hafer, PhD, is a molecular biologist at UMass Chan Medical School, the academic partner of UMass Memorial Health.\n\nOther related articles by:\n\n[Antigen](https:\/\/www.ummhealth.org\/tags\/antigen) \\| [COVID-19](https:\/\/www.ummhealth.org\/tags\/covid-19) \\| [genetic evidence](https:\/\/www.ummhealth.org\/tags\/genetic-evidence) \\| [Nathaniel Hafer](https:\/\/www.ummhealth.org\/tags\/nathaniel-hafer) \\| [PCR](https:\/\/www.ummhealth.org\/tags\/pcr) \\| [testing](https:\/\/www.ummhealth.org\/tags\/testing) \\| [UMass Chan Medical School](https:\/\/www.ummhealth.org\/tags\/umass-chan-medical-school)\n\nNote: The content of this blog is for informational purposes only. It is not intended for use as diagnosis or treatment of a health problem or as a substitute for the professional consultation of a physician or qualified health care provider. If you have specific questions or concerns regarding a health or medical condition, contact your physician or a licensed health care professional.\n## Not a Subscriber? Sign up for Simply Well Today.\n## Donate to UMass Memorial Health\nLearn more about giving to UMass Memorial Health\n\n[Donate Now](https:\/\/host.nxt.blackbaud.com\/donor-form?svcid=tcs&formId=93b69188-5a97-4e5c-ad95-f9a4910838ea&envid=p-dRCy9b-paUSolQoL8q1t-A&zone=usa)\n\n### Connect with us\n[Facebook](https:\/\/www.facebook.com\/umassmemorialhealth)\n\n[Linkedin](https:\/\/www.linkedin.com\/company\/umassmemorialhealth)\n\n[Instagram](https:\/\/www.instagram.com\/umassmemorial\/)\n\n[Threads](https:\/\/www.threads.net\/@umassmemorial)\n\n[X](https:\/\/twitter.com\/umassmemorial)\n\n[![Home](https:\/\/www.ummhealth.org\/sites\/default\/files\/ummh_logo_color.png)](https:\/\/www.ummhealth.org\/)\n\n[855-UMASS-MD (855-862-7763)](tel:8558627763)\n\n[The Clinical Partner of UMass Chan Medical School](https:\/\/www.umassmed.edu\/)\n\n## Footer Menu\n- [Patients and Visitors](https:\/\/www.ummhealth.org\/patients-visitors)\n  - [Patient and Visitor Information](https:\/\/www.ummhealth.org\/patients-visitors)\n  - [Clinical Trials](https:\/\/www.conqueringdiseases.org\/)\n  - [Find a Doctor](https:\/\/physicians.umassmemorial.org\/)\n  - [Insurance Plans Accepted](https:\/\/www.ummhealth.org\/patients-visitors\/insurance-information-patients\/insurance-plans-accepted)\n  - [Interpreter Services](https:\/\/www.ummhealth.org\/patients-visitors\/interpreter-services)\n  - [Make an Appointment](https:\/\/www.ummhealth.org\/patients-visitors\/make-appointment)\n  - [myChart](https:\/\/www.ummhealth.org\/patients-visitors\/mychart)\n  - [Pay My Bill](https:\/\/www.ummhealth.org\/patients-visitors\/pay-bills-online)\n  - [Request Medical Records](https:\/\/www.ummhealth.org\/patients-visitors\/medical-records)\n  - [Services and Treatments](https:\/\/www.ummhealth.org\/services-treatments)\n  - [Simply Well Health Blog](https:\/\/www.ummhealth.org\/simply-well)\n  - [Price Transparency](https:\/\/www.ummhealth.org\/patients-visitors\/price-transparency)\n- [About Us](https:\/\/www.ummhealth.org\/about-us)\n  - [About UMass Memorial Health](https:\/\/www.ummhealth.org\/about-us)\n  - [Contact](https:\/\/www.ummhealth.org\/contact)\n  - [Donate Now](https:\/\/www.ummhealth.org\/giving)\n  - [Events](https:\/\/www.ummhealth.org\/events)\n  - [Media Library](https:\/\/www.ummhealth.org\/about-us\/media-library)\n  - [Newsroom](https:\/\/www.ummhealth.org\/about-us\/newsroom)\n  - [Nondiscrimination Notice](https:\/\/www.ummhealth.org\/about-us\/nondiscrimination-notice)\n- [Our System of Care](https:\/\/www.ummhealth.org\/about-us)\n  - [UMass Memorial Medical Center](https:\/\/www.ummhealth.org\/umass-memorial-medical-center)\n  - [Children’s Medical Center](https:\/\/www.ummhealth.org\/childrens-medical-center)\n  - [Harrington](https:\/\/www.ummhealth.org\/harrington)\n  - [HealthAlliance-Clinton Hospital](https:\/\/www.ummhealth.org\/healthalliance-clinton-hospital)\n  - [Milford Regional](https:\/\/www.milfordregional.org\/)\n  - [Community Healthlink](https:\/\/www.communityhealthlink.org\/)\n  - [UMass Memorial Medical Group](https:\/\/www.ummhealth.org\/umass-memorial-medical-group)\n\n## Legal Menu\n- [Website Terms of Use](https:\/\/www.ummhealth.org\/website-terms-use-statement)\n- [SMS Terms of Use](https:\/\/www.ummhealth.org\/sms-terms-use)\n- [Joint Notice of Privacy Practices](https:\/\/www.ummhealth.org\/patients-visitors\/joint-notice-privacy-practices)\n\nCopyright © 2026 UMass Memorial Health. All rights reserved.\n\n![Woosox Logo](https:\/\/www.ummhealth.org\/sites\/default\/files\/styles\/large\/public\/2024-04\/woosox_logo.png.webp?itok=o27TJAdb)\n\nExclusive Health Care Provider of the Worcester Red Sox.","attrs_readable_markdown":"At this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests?\n\n[**I’m a molecular biologist**](https:\/\/profiles.umassmed.edu\/display\/14945561), and since April 2020, I’ve been part of a team [**working on a National Institutes of Health-funded program called RADx**](https:\/\/www.nih.gov\/research-training\/medical-research-initiatives\/radx) that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19.\n\nTwo major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as [**PCR tests**](https:\/\/www.fda.gov\/consumers\/consumer-updates\/coronavirus-disease-2019-testing-basics)– and [**antigen tests**](https:\/\/theconversation.com\/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977). Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests?\n\n[![A person in a white coat with gloves placing samples into a red laboratory device.](https:\/\/images.theconversation.com\/files\/430518\/original\/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https:\/\/images.theconversation.com\/files\/430518\/original\/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip)\n\nPCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform. [**Karl Mumm via Wikimedia Commons**](https:\/\/commons.wikimedia.org\/wiki\/File:PCR_masina_kasutamine.jpg#\/media\/File:PCR_masina_kasutamine.jpg)**,** [**CC BY-SA**](http:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/)\n## Looking for Genetic Evidence\nThe first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva.\n\nFor PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a[**polymerase chain reaction**](https:\/\/www.genome.gov\/about-genomics\/fact-sheets\/Polymerase-Chain-Reaction-Fact-Sheet). A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase, and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA.\n\nLaboratory machines [**repeat these heating and cooling cycles 30 to 40 times**](https:\/\/www.jove.com\/v\/5056\/pcr-the-polymerase-chain-reaction), doubling the DNA until there are a [**billion copies of the original piece**](https:\/\/www.thermofisher.com\/us\/en\/home\/life-science\/cloning\/cloning-learning-center\/invitrogen-school-of-molecular-biology\/pcr-education\/pcr-reagents-enzymes\/pcr-basics.html). The amplified sequence contains fluorescent dye that is read by a machine.\n\nThe amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a [**highly sensitive and accurate test**](https:\/\/medlineplus.gov\/lab-tests\/pcr-tests\/). With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2.\n\nHowever, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take [**an hour or more from start to finish**](https:\/\/dx.doi.org\/10.1016%2Fj.bdq.2017.05.002). Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection, and reporting, it can take [**from 12 hours to five days for a person to get results back**](https:\/\/my.clevelandclinic.org\/health\/diagnostics\/21462-covid-19-and-pcr-testing). And finally, they aren’t cheap at \\$100 or more per test.\n\n[![Two small white plastic tests with single lines showing negative tests results and a circular depression to place a sample.](https:\/\/images.theconversation.com\/files\/430526\/original\/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https:\/\/images.theconversation.com\/files\/430526\/original\/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip)\n\nRapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests. [**Lennardywlee via Wikimedia Commons**](https:\/\/commons.wikimedia.org\/wiki\/File:COVID-19_rapid_test.jpg#\/media\/File:COVID-19_rapid_test.jpg)**,** [**CC BY-SA**](http:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/)\n## Antigen Tests\n[**Rapid, accurate tests are essential**](https:\/\/theconversation.com\/over-the-counter-rapid-antigen-tests-can-help-slow-the-spread-of-covid-19-heres-how-to-use-them-effectively-166869)to contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results.\n\nAntigen tests, the other major type of coronavirus test, while much faster, are less accurate. Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus.\n\nTo run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that [**has antibodies specific to SARS-CoV-2 painted on it in a thin line**](https:\/\/theconversation.com\/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977).\n\nJust like antibodies in your body, the ones on the test strip will [**bind to any antigen in the sample**](https:\/\/labtestsonline.org\/tests\/covid-19-antigen-test). If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2.\n\nAntigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – [**even at home**](https:\/\/theconversation.com\/rapid-screening-tests-that-prioritize-speed-over-accuracy-could-be-key-to-ending-the-coronavirus-pandemic-143882). They also produce results quickly, [**typically in less than 15 minutes**](https:\/\/theconversation.com\/will-the-new-15-minute-covid-19-test-solve-us-testing-problems-145285). Another benefit is that these tests can be relatively inexpensive at [**around \\$10-\\$15 per test**](https:\/\/www.cvs.com\/shop\/home-health-care\/home-tests\/home-covid-test).\n\nAntigen tests do have some drawbacks. Depending on the situation, they can be [**less accurate than PCR tests**](https:\/\/doi.org\/10.1093\/infdis\/jiab337). When a person is symptomatic or has a lot of virus in their system, [**antigen tests are very accurate**](https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC7799021\/). However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can [**miss early cases of COVID-19**](https:\/\/doi.org\/10.1038\/d41586-021-00332-4). It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected.\n\n## More Tests, Better Knowledge\nA few antigen tests are already available over the counter, and on October 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public.\n\nAt RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used.\n\nUnderstanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you.\n\nThis post is republished from [**The Conversation**](https:\/\/theconversation.com\/us) under a Creative Commons license. Read the [**original article**](https:\/\/theconversation.com\/whats-the-difference-between-a-pcr-and-antigen-covid-19-test-a-molecular-biologist-explains-170917). Author Nathaniel Hafer, PhD, is a molecular biologist at UMass Chan Medical School, the academic partner of UMass Memorial Health.","meta_canonical":null}

3. Robots.txt Check

Query:

Response:

4. Spam/Ban Check

Query:

Response:

5. Seen Status Check

ℹ️ Skipped - page is already crawled

📄

INDEXABLE

✅

CRAWLED

1 day ago

🤖

ROBOTS ALLOWED

Page Info Filters

Filter	Status	Condition	Details
HTTP status	PASS	`download_http_code = 200`	HTTP 200
Age cutoff	PASS	`download_stamp > now() - 6 MONTH`	0.1 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

Page Details

Property	Value
URL	https://www.ummhealth.org/simply-well/the-difference-between-pcr-and-antigen-covid-19-tests
Last Crawled	2026-04-17 14:52:05 (1 day ago)
First Indexed	2025-01-14 10:55:35 (1 year ago)
HTTP Status Code	200
Meta Title	The Difference Between PCR and Antigen COVID-19 Tests - SimplyWell - UMass Memorial Health
Meta Description	You or someone you know has probably received a COVID-19 test. But do you know which kind of test you got and its strengths and weaknesses?
Meta Canonical	null
Boilerpipe Text	At this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests? I’m a molecular biologist , and since April 2020, I’ve been part of a team working on a National Institutes of Health-funded program called RADx that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19. Two major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as PCR tests – and antigen tests . Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests? PCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform. Karl Mumm via Wikimedia Commons , CC BY-SA Looking for Genetic Evidence The first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva. For PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a polymerase chain reaction . A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase, and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA. Laboratory machines repeat these heating and cooling cycles 30 to 40 times , doubling the DNA until there are a billion copies of the original piece . The amplified sequence contains fluorescent dye that is read by a machine. The amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a highly sensitive and accurate test . With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2. However, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take an hour or more from start to finish . Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection, and reporting, it can take from 12 hours to five days for a person to get results back . And finally, they aren’t cheap at $100 or more per test. Rapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests. Lennardywlee via Wikimedia Commons , CC BY-SA Antigen Tests Rapid, accurate tests are essential to contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results. Antigen tests, the other major type of coronavirus test, while much faster, are less accurate. Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus. To run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that has antibodies specific to SARS-CoV-2 painted on it in a thin line . Just like antibodies in your body, the ones on the test strip will bind to any antigen in the sample . If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2. Antigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – even at home . They also produce results quickly, typically in less than 15 minutes . Another benefit is that these tests can be relatively inexpensive at around $10-$15 per test . Antigen tests do have some drawbacks. Depending on the situation, they can be less accurate than PCR tests . When a person is symptomatic or has a lot of virus in their system, antigen tests are very accurate . However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can miss early cases of COVID-19 . It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected. More Tests, Better Knowledge A few antigen tests are already available over the counter, and on October 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public. At RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used. Understanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you. This post is republished from The Conversation under a Creative Commons license. Read the original article . Author Nathaniel Hafer, PhD, is a molecular biologist at UMass Chan Medical School, the academic partner of UMass Memorial Health.
Markdown	[Skip to main content](https://www.ummhealth.org/simply-well/the-difference-between-pcr-and-antigen-covid-19-tests#main-content) - [Careers](https://www.ummhealth.org/careers) - [myChart](https://mychartonline.umassmemorial.org/MyChart/Authentication/Login) - [Patients and Visitors](https://www.ummhealth.org/patients-visitors) - [Health Professionals](https://www.ummhealth.org/health-professionals) - [Donate](https://www.ummhealth.org/giving) I want to... Choose here - [Request Medical Records](https://www.ummhealth.org/patients-visitors/medical-records) - [Volunteer](https://www.ummhealth.org/giving/ways-to-give/volunteer-services) - [Explore Careers](https://www.ummhealth.org/careers) - [Pay My Bill](https://www.ummhealth.org/patients-visitors/pay-bills-online) - [Learn about Insurance Plans Accepted](https://www.ummhealth.org/patients-visitors/insurance-information-patients) - [Find a Doctor](https://physicians.umassmemorial.org/) - [Make an Appointment](https://www.ummhealth.org/patients-visitors/make-appointment) - [Go to Patients and Visitors](https://www.ummhealth.org/patients-visitors) - [Explore Mindfulness](https://www.ummhealth.org/services-treatments/center-mindfulness) - [Learn about myChart](https://www.ummhealth.org/patients-visitors/mychart) - [Go to EpicCare Link](https://www.ummhealth.org/health-professionals/epiccare-link) Open translate options Open Search ![UMM Logo](https://www.ummhealth.org/sites/default/files/ummh_logo_color.png) [855-UMASS-MD (855-862-7763)](tel:8558627763) [![Home](https://www.ummhealth.org/sites/default/files/ummh_logo_color.png)](https://www.ummhealth.org/) Open Search ![UMM Logo](https://www.ummhealth.org/sites/default/files/ummh_logo_color.png) The Clinical Partner of UMass Chan Medical School - [All Locations](https://www.ummhealth.org/locations) Toggle submenu ## All Locations [View all Locations](https://www.ummhealth.org/locations) Find a location by type, service, treatment or distance to you. - Our System of Care - [UMass Memorial Medical Center](https://www.ummhealth.org/umass-memorial-medical-center) - [Children's Medical Center](https://www.ummhealth.org/childrens-medical-center) - [Harrington](https://www.ummhealth.org/harrington) - [HealthAlliance-Clinton Hospital](https://www.ummhealth.org/healthalliance-clinton-hospital) - [Milford Regional](https://www.ummhealth.org/milford-regional/about-us) - [Community Healthlink](https://www.ummhealth.org/community-healthlink/about-us) - [UMass Memorial Medical Group](https://www.ummhealth.org/umass-memorial-medical-group) - Locations by - [Affiliations](https://www.ummhealth.org/locations?field_facility_type_target_id=1425) - [Behavioral Health Services](https://www.ummhealth.org/locations?field_facility_type_target_id=32) - [Corporate Offices](https://www.ummhealth.org/locations?field_facility_type_target_id=1424) - [Emergency Care](https://www.ummhealth.org/locations?field_facility_type_target_id=1421) - [Imaging Centers](https://www.ummhealth.org/locations?field_facility_type_target_id=35) - [Hospital Campuses](https://www.ummhealth.org/locations?field_facility_type_target_id=34) - [Lab Services](https://www.ummhealth.org/locations?field_services_target_id_entityreference_filter=11730) - [Outpatient Health Care Centers](https://www.ummhealth.org/locations?field_facility_type_target_id=36) - [Primary Care Offices](https://www.ummhealth.org/locations?field_facility_type_target_id=23) - [Urgent Care Centers](https://www.ummhealth.org/locations?field_facility_type_target_id=24) - [Find a Doctor](https://physicians.umassmemorial.org/) - [Services and Treatments](https://www.ummhealth.org/services-treatments) Toggle submenu ### View Alphabetically - [a](https://www.ummhealth.org/services-and-treatments?title=1) - [b](https://www.ummhealth.org/services-and-treatments?title=2) - [c](https://www.ummhealth.org/services-and-treatments?title=3) - [d](https://www.ummhealth.org/services-and-treatments?title=4) - [e](https://www.ummhealth.org/services-and-treatments?title=5) - [f](https://www.ummhealth.org/services-and-treatments?title=6) - [g](https://www.ummhealth.org/services-and-treatments?title=7) - [h](https://www.ummhealth.org/services-and-treatments?title=8) - [i](https://www.ummhealth.org/services-and-treatments?title=9) - j - [k](https://www.ummhealth.org/services-and-treatments?title=11) - [l](https://www.ummhealth.org/services-and-treatments?title=12) - [m](https://www.ummhealth.org/services-and-treatments?title=13) - [n](https://www.ummhealth.org/services-and-treatments?title=14) - [o](https://www.ummhealth.org/services-and-treatments?title=15) - [p](https://www.ummhealth.org/services-and-treatments?title=16) - q - [r](https://www.ummhealth.org/services-and-treatments?title=18) - [s](https://www.ummhealth.org/services-and-treatments?title=19) - [t](https://www.ummhealth.org/services-and-treatments?title=20) - [u](https://www.ummhealth.org/services-and-treatments?title=21) - [v](https://www.ummhealth.org/services-and-treatments?title=22) - [w](https://www.ummhealth.org/services-and-treatments?title=23) - x - [y](https://www.ummhealth.org/services-and-treatments?title=25) - z ## Services and Treatments - [View All Services and Treatments](https://www.ummhealth.org/services-treatments) - [Urgent Care](https://www.ummhealth.org/services-treatments/emergency-care/urgent-care) - [General Surgery](https://www.ummhealth.org/services-treatments/surgery/general-surgery) - [Center for Mindfulness](https://www.ummhealth.org/services-treatments/center-mindfulness) - [Orthopedics](https://www.ummhealth.org/services-treatments/orthopedics) - [Radiology and Imaging](https://www.ummhealth.org/services-treatments/radiology-and-imaging) - [Gastroenterology](https://www.ummhealth.org/services-treatments/gastroenterology) - [Primary Care](https://www.ummhealth.org/services-treatments/primary-care) - [Diabetes](https://www.ummhealth.org/services-treatments/diabetes) - [Heart and Vascular](https://www.ummhealth.org/services-treatments/heart-and-vascular-care) - [Pediatrics](https://www.ummhealth.org/services-treatments?field_entities_target_id=19) [Health Library](https://www.ummhealth.org/health-library) Your trusted resource for all types of health conditions, providing you the knowledge to make informed decisions about your health. [Simply Well](https://www.ummhealth.org/simply-well) Content to help you live healthy and well. Enhancing your lifestyle is part of our relentless pursuit of helping you live a healthy life. Menu - [All Locations](https://www.ummhealth.org/locations) Toggle submenu ## All Locations [View all Locations](https://www.ummhealth.org/locations) Find a location by type, service, treatment or distance to you. - Our System of Care - [UMass Memorial Medical Center](https://www.ummhealth.org/umass-memorial-medical-center) - [Children's Medical Center](https://www.ummhealth.org/childrens-medical-center) - [Harrington](https://www.ummhealth.org/harrington) - [HealthAlliance-Clinton Hospital](https://www.ummhealth.org/healthalliance-clinton-hospital) - [Milford Regional](https://www.ummhealth.org/milford-regional/about-us) - [Community Healthlink](https://www.ummhealth.org/community-healthlink/about-us) - [UMass Memorial Medical Group](https://www.ummhealth.org/umass-memorial-medical-group) - Locations by - [Affiliations](https://www.ummhealth.org/locations?field_facility_type_target_id=1425) - [Behavioral Health Services](https://www.ummhealth.org/locations?field_facility_type_target_id=32) - [Corporate Offices](https://www.ummhealth.org/locations?field_facility_type_target_id=1424) - [Emergency Care](https://www.ummhealth.org/locations?field_facility_type_target_id=1421) - [Imaging Centers](https://www.ummhealth.org/locations?field_facility_type_target_id=35) - [Hospital Campuses](https://www.ummhealth.org/locations?field_facility_type_target_id=34) - [Lab Services](https://www.ummhealth.org/locations?field_services_target_id_entityreference_filter=11730) - [Outpatient Health Care Centers](https://www.ummhealth.org/locations?field_facility_type_target_id=36) - [Primary Care Offices](https://www.ummhealth.org/locations?field_facility_type_target_id=23) - [Urgent Care Centers](https://www.ummhealth.org/locations?field_facility_type_target_id=24) - [Find a Doctor](https://physicians.umassmemorial.org/) - [Services and Treatments](https://www.ummhealth.org/services-treatments) Toggle submenu ### View Alphabetically - [a](https://www.ummhealth.org/services-and-treatments?title=1) - [b](https://www.ummhealth.org/services-and-treatments?title=2) - [c](https://www.ummhealth.org/services-and-treatments?title=3) - [d](https://www.ummhealth.org/services-and-treatments?title=4) - [e](https://www.ummhealth.org/services-and-treatments?title=5) - [f](https://www.ummhealth.org/services-and-treatments?title=6) - [g](https://www.ummhealth.org/services-and-treatments?title=7) - [h](https://www.ummhealth.org/services-and-treatments?title=8) - [i](https://www.ummhealth.org/services-and-treatments?title=9) - j - [k](https://www.ummhealth.org/services-and-treatments?title=11) - [l](https://www.ummhealth.org/services-and-treatments?title=12) - [m](https://www.ummhealth.org/services-and-treatments?title=13) - [n](https://www.ummhealth.org/services-and-treatments?title=14) - [o](https://www.ummhealth.org/services-and-treatments?title=15) - [p](https://www.ummhealth.org/services-and-treatments?title=16) - q - [r](https://www.ummhealth.org/services-and-treatments?title=18) - [s](https://www.ummhealth.org/services-and-treatments?title=19) - [t](https://www.ummhealth.org/services-and-treatments?title=20) - [u](https://www.ummhealth.org/services-and-treatments?title=21) - [v](https://www.ummhealth.org/services-and-treatments?title=22) - [w](https://www.ummhealth.org/services-and-treatments?title=23) - x - [y](https://www.ummhealth.org/services-and-treatments?title=25) - z ## Services and Treatments - [View All Services and Treatments](https://www.ummhealth.org/services-treatments) - [Urgent Care](https://www.ummhealth.org/services-treatments/emergency-care/urgent-care) - [General Surgery](https://www.ummhealth.org/services-treatments/surgery/general-surgery) - [Center for Mindfulness](https://www.ummhealth.org/services-treatments/center-mindfulness) - [Orthopedics](https://www.ummhealth.org/services-treatments/orthopedics) - [Radiology and Imaging](https://www.ummhealth.org/services-treatments/radiology-and-imaging) - [Gastroenterology](https://www.ummhealth.org/services-treatments/gastroenterology) - [Primary Care](https://www.ummhealth.org/services-treatments/primary-care) - [Diabetes](https://www.ummhealth.org/services-treatments/diabetes) - [Heart and Vascular](https://www.ummhealth.org/services-treatments/heart-and-vascular-care) - [Pediatrics](https://www.ummhealth.org/services-treatments?field_entities_target_id=19) [Health Library](https://www.ummhealth.org/health-library) Your trusted resource for all types of health conditions, providing you the knowledge to make informed decisions about your health. [Simply Well](https://www.ummhealth.org/simply-well) Content to help you live healthy and well. Enhancing your lifestyle is part of our relentless pursuit of helping you live a healthy life. I want to... Choose here - [Request Medical Records](https://www.ummhealth.org/patients-visitors/medical-records) - [Volunteer](https://www.ummhealth.org/giving/ways-to-give/volunteer-services) - [Explore Careers](https://www.ummhealth.org/careers) - [Pay My Bill](https://www.ummhealth.org/patients-visitors/pay-bills-online) - [Learn about Insurance Plans Accepted](https://www.ummhealth.org/patients-visitors/insurance-information-patients) - [Find a Doctor](https://physicians.umassmemorial.org/) - [Make an Appointment](https://www.ummhealth.org/patients-visitors/make-appointment) - [Go to Patients and Visitors](https://www.ummhealth.org/patients-visitors) - [Explore Mindfulness](https://www.ummhealth.org/services-treatments/center-mindfulness) - [Learn about myChart](https://www.ummhealth.org/patients-visitors/mychart) - [Go to EpicCare Link](https://www.ummhealth.org/health-professionals/epiccare-link) - [Careers](https://www.ummhealth.org/careers) - [myChart](https://mychartonline.umassmemorial.org/MyChart/Authentication/Login) - [Patients and Visitors](https://www.ummhealth.org/patients-visitors) - [Health Professionals](https://www.ummhealth.org/health-professionals) - [Donate](https://www.ummhealth.org/giving) The Clinical Partner of UMass Chan Medical School [SIMPLY WELL BLOG](https://www.ummhealth.org/simply-well) [![The Simply Well logo with the text 'Conversations to keep you healthy and well'.](https://www.ummhealth.org/sites/default/files/styles/entity_logo/public/2025-01/Simply_Well_logo_500x114.png.webp?itok=UJWF9gnn)](https://www.ummhealth.org/simply-well) - [Parenting](https://www.ummhealth.org/simply-well/parenting) Toggle submenu - [Infants and Toddlers](https://www.ummhealth.org/simply-well/parenting/infants-toddlers) - [School Age](https://www.ummhealth.org/simply-well/parenting/school-age) - [Teen](https://www.ummhealth.org/simply-well/parenting/teen) - [Food and Fitness](https://www.ummhealth.org/simply-well/food-and-fitness) Toggle submenu - [Exercise](https://www.ummhealth.org/simply-well/food-and-fitness/exercise) - [Healthy Eating](https://www.ummhealth.org/simply-well/food-and-fitness/healthy-eating) - [Recipes](https://www.ummhealth.org/simply-well/food-and-fitness/recipes) - [Sports](https://www.ummhealth.org/simply-well/food-and-fitness/sports) - [Prevention and Wellness](https://www.ummhealth.org/simply-well/prevention-and-wellness) - [Mind Matters](https://www.ummhealth.org/simply-well/mind-matters) Toggle submenu - [Mental Health](https://www.ummhealth.org/simply-well/mind-matters/mental-health) - [Mindfulness](https://www.ummhealth.org/simply-well/mind-matters/mindfulness) - [Care and Conditions](https://www.ummhealth.org/simply-well/care-and-conditions) Toggle submenu - [Cancer](https://www.ummhealth.org/simply-well/care-and-conditions/cancer) - [Colorectal](https://www.ummhealth.org/simply-well/care-and-conditions/colorectal) - [Diabetes](https://www.ummhealth.org/simply-well/care-and-conditions/diabetes) - [Heart](https://www.ummhealth.org/simply-well/care-and-conditions/heart) - [Joint Replacement](https://www.ummhealth.org/simply-well/care-and-conditions/joint-replacement) - [Orthopedics](https://www.ummhealth.org/simply-well/care-and-conditions/orthopedics) - [Women's Health](https://www.ummhealth.org/simply-well/care-and-conditions/womens-health) - [About Us](https://www.ummhealth.org/simply-well/about-simply-well) - [Search](https://www.ummhealth.org/) Toggle submenu 1\.19.22 # The Difference Between PCR and Antigen COVID-19 Tests ![](https://www.ummhealth.org/sites/default/files/styles/header_hero/public/featured_images/COIVD-19-swab-and-vile-resized.jpg.webp?itok=QInrp7wX) ## Breadcrumb 1. [Home](https://www.ummhealth.org/) › 2. [Simply Well](https://www.ummhealth.org/simply-well) [Facebook]("Facebook") [X]("X") [Linkedin]("Linkedin") [Email]("Email") [Copy Link]("Copy Link") [Print]("Print") At this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests? [I’m a molecular biologist](https://profiles.umassmed.edu/display/14945561), and since April 2020, I’ve been part of a team [working on a National Institutes of Health-funded program called RADx](https://www.nih.gov/research-training/medical-research-initiatives/radx) that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19. Two major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as [PCR tests](https://www.fda.gov/consumers/consumer-updates/coronavirus-disease-2019-testing-basics)– and [antigen tests](https://theconversation.com/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977). Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests? [![A person in a white coat with gloves placing samples into a red laboratory device.](https://images.theconversation.com/files/430518/original/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https://images.theconversation.com/files/430518/original/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip) PCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform. [Karl Mumm via Wikimedia Commons](https://commons.wikimedia.org/wiki/File:PCR_masina_kasutamine.jpg#/media/File:PCR_masina_kasutamine.jpg), [CC BY-SA](http://creativecommons.org/licenses/by-sa/4.0/) ## Looking for Genetic Evidence The first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva. For PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a[polymerase chain reaction](https://www.genome.gov/about-genomics/fact-sheets/Polymerase-Chain-Reaction-Fact-Sheet). A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase, and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA. Laboratory machines [repeat these heating and cooling cycles 30 to 40 times](https://www.jove.com/v/5056/pcr-the-polymerase-chain-reaction), doubling the DNA until there are a [billion copies of the original piece](https://www.thermofisher.com/us/en/home/life-science/cloning/cloning-learning-center/invitrogen-school-of-molecular-biology/pcr-education/pcr-reagents-enzymes/pcr-basics.html). The amplified sequence contains fluorescent dye that is read by a machine. The amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a [highly sensitive and accurate test](https://medlineplus.gov/lab-tests/pcr-tests/). With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2. However, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take [an hour or more from start to finish](https://dx.doi.org/10.1016%2Fj.bdq.2017.05.002). Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection, and reporting, it can take [from 12 hours to five days for a person to get results back](https://my.clevelandclinic.org/health/diagnostics/21462-covid-19-and-pcr-testing). And finally, they aren’t cheap at \$100 or more per test. [![Two small white plastic tests with single lines showing negative tests results and a circular depression to place a sample.](https://images.theconversation.com/files/430526/original/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https://images.theconversation.com/files/430526/original/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip) Rapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests. [Lennardywlee via Wikimedia Commons](https://commons.wikimedia.org/wiki/File:COVID-19_rapid_test.jpg#/media/File:COVID-19_rapid_test.jpg), [CC BY-SA](http://creativecommons.org/licenses/by-sa/4.0/) ## Antigen Tests [Rapid, accurate tests are essential](https://theconversation.com/over-the-counter-rapid-antigen-tests-can-help-slow-the-spread-of-covid-19-heres-how-to-use-them-effectively-166869)to contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results. Antigen tests, the other major type of coronavirus test, while much faster, are less accurate. Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus. To run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that [has antibodies specific to SARS-CoV-2 painted on it in a thin line](https://theconversation.com/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977). Just like antibodies in your body, the ones on the test strip will [bind to any antigen in the sample](https://labtestsonline.org/tests/covid-19-antigen-test). If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2. Antigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – [even at home](https://theconversation.com/rapid-screening-tests-that-prioritize-speed-over-accuracy-could-be-key-to-ending-the-coronavirus-pandemic-143882). They also produce results quickly, [typically in less than 15 minutes](https://theconversation.com/will-the-new-15-minute-covid-19-test-solve-us-testing-problems-145285). Another benefit is that these tests can be relatively inexpensive at [around \$10-\$15 per test](https://www.cvs.com/shop/home-health-care/home-tests/home-covid-test). Antigen tests do have some drawbacks. Depending on the situation, they can be [less accurate than PCR tests](https://doi.org/10.1093/infdis/jiab337). When a person is symptomatic or has a lot of virus in their system, [antigen tests are very accurate](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7799021/). However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can [miss early cases of COVID-19](https://doi.org/10.1038/d41586-021-00332-4). It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected. ## More Tests, Better Knowledge A few antigen tests are already available over the counter, and on October 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public. At RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used. Understanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you. This post is republished from [The Conversation](https://theconversation.com/us) under a Creative Commons license. Read the [original article](https://theconversation.com/whats-the-difference-between-a-pcr-and-antigen-covid-19-test-a-molecular-biologist-explains-170917). Author Nathaniel Hafer, PhD, is a molecular biologist at UMass Chan Medical School, the academic partner of UMass Memorial Health. Other related articles by: [Antigen](https://www.ummhealth.org/tags/antigen) \\| [COVID-19](https://www.ummhealth.org/tags/covid-19) \\| [genetic evidence](https://www.ummhealth.org/tags/genetic-evidence) \\| [Nathaniel Hafer](https://www.ummhealth.org/tags/nathaniel-hafer) \\| [PCR](https://www.ummhealth.org/tags/pcr) \\| [testing](https://www.ummhealth.org/tags/testing) \\| [UMass Chan Medical School](https://www.ummhealth.org/tags/umass-chan-medical-school) Note: The content of this blog is for informational purposes only. It is not intended for use as diagnosis or treatment of a health problem or as a substitute for the professional consultation of a physician or qualified health care provider. If you have specific questions or concerns regarding a health or medical condition, contact your physician or a licensed health care professional. ## Not a Subscriber? Sign up for Simply Well Today. ## Donate to UMass Memorial Health Learn more about giving to UMass Memorial Health [Donate Now](https://host.nxt.blackbaud.com/donor-form?svcid=tcs&formId=93b69188-5a97-4e5c-ad95-f9a4910838ea&envid=p-dRCy9b-paUSolQoL8q1t-A&zone=usa) ### Connect with us [Facebook](https://www.facebook.com/umassmemorialhealth) [Linkedin](https://www.linkedin.com/company/umassmemorialhealth) [Instagram](https://www.instagram.com/umassmemorial/) [Threads](https://www.threads.net/@umassmemorial) [X](https://twitter.com/umassmemorial) [![Home](https://www.ummhealth.org/sites/default/files/ummh_logo_color.png)](https://www.ummhealth.org/) [855-UMASS-MD (855-862-7763)](tel:8558627763) [The Clinical Partner of UMass Chan Medical School](https://www.umassmed.edu/) ## Footer Menu - [Patients and Visitors](https://www.ummhealth.org/patients-visitors) - [Patient and Visitor Information](https://www.ummhealth.org/patients-visitors) - [Clinical Trials](https://www.conqueringdiseases.org/) - [Find a Doctor](https://physicians.umassmemorial.org/) - [Insurance Plans Accepted](https://www.ummhealth.org/patients-visitors/insurance-information-patients/insurance-plans-accepted) - [Interpreter Services](https://www.ummhealth.org/patients-visitors/interpreter-services) - [Make an Appointment](https://www.ummhealth.org/patients-visitors/make-appointment) - [myChart](https://www.ummhealth.org/patients-visitors/mychart) - [Pay My Bill](https://www.ummhealth.org/patients-visitors/pay-bills-online) - [Request Medical Records](https://www.ummhealth.org/patients-visitors/medical-records) - [Services and Treatments](https://www.ummhealth.org/services-treatments) - [Simply Well Health Blog](https://www.ummhealth.org/simply-well) - [Price Transparency](https://www.ummhealth.org/patients-visitors/price-transparency) - [About Us](https://www.ummhealth.org/about-us) - [About UMass Memorial Health](https://www.ummhealth.org/about-us) - [Contact](https://www.ummhealth.org/contact) - [Donate Now](https://www.ummhealth.org/giving) - [Events](https://www.ummhealth.org/events) - [Media Library](https://www.ummhealth.org/about-us/media-library) - [Newsroom](https://www.ummhealth.org/about-us/newsroom) - [Nondiscrimination Notice](https://www.ummhealth.org/about-us/nondiscrimination-notice) - [Our System of Care](https://www.ummhealth.org/about-us) - [UMass Memorial Medical Center](https://www.ummhealth.org/umass-memorial-medical-center) - [Children’s Medical Center](https://www.ummhealth.org/childrens-medical-center) - [Harrington](https://www.ummhealth.org/harrington) - [HealthAlliance-Clinton Hospital](https://www.ummhealth.org/healthalliance-clinton-hospital) - [Milford Regional](https://www.milfordregional.org/) - [Community Healthlink](https://www.communityhealthlink.org/) - [UMass Memorial Medical Group](https://www.ummhealth.org/umass-memorial-medical-group) ## Legal Menu - [Website Terms of Use](https://www.ummhealth.org/website-terms-use-statement) - [SMS Terms of Use](https://www.ummhealth.org/sms-terms-use) - [Joint Notice of Privacy Practices](https://www.ummhealth.org/patients-visitors/joint-notice-privacy-practices) Copyright © 2026 UMass Memorial Health. All rights reserved. ![Woosox Logo](https://www.ummhealth.org/sites/default/files/styles/large/public/2024-04/woosox_logo.png.webp?itok=o27TJAdb) Exclusive Health Care Provider of the Worcester Red Sox.
Readable Markdown	At this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests? [I’m a molecular biologist](https://profiles.umassmed.edu/display/14945561), and since April 2020, I’ve been part of a team [working on a National Institutes of Health-funded program called RADx](https://www.nih.gov/research-training/medical-research-initiatives/radx) that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19. Two major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as [PCR tests](https://www.fda.gov/consumers/consumer-updates/coronavirus-disease-2019-testing-basics)– and [antigen tests](https://theconversation.com/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977). Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests? [![A person in a white coat with gloves placing samples into a red laboratory device.](https://images.theconversation.com/files/430518/original/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https://images.theconversation.com/files/430518/original/file-20211105-10546-1gy5rvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip) PCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform. [Karl Mumm via Wikimedia Commons](https://commons.wikimedia.org/wiki/File:PCR_masina_kasutamine.jpg#/media/File:PCR_masina_kasutamine.jpg), [CC BY-SA](http://creativecommons.org/licenses/by-sa/4.0/) ## Looking for Genetic Evidence The first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva. For PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a[polymerase chain reaction](https://www.genome.gov/about-genomics/fact-sheets/Polymerase-Chain-Reaction-Fact-Sheet). A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase, and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA. Laboratory machines [repeat these heating and cooling cycles 30 to 40 times](https://www.jove.com/v/5056/pcr-the-polymerase-chain-reaction), doubling the DNA until there are a [billion copies of the original piece](https://www.thermofisher.com/us/en/home/life-science/cloning/cloning-learning-center/invitrogen-school-of-molecular-biology/pcr-education/pcr-reagents-enzymes/pcr-basics.html). The amplified sequence contains fluorescent dye that is read by a machine. The amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a [highly sensitive and accurate test](https://medlineplus.gov/lab-tests/pcr-tests/). With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2. However, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take [an hour or more from start to finish](https://dx.doi.org/10.1016%2Fj.bdq.2017.05.002). Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection, and reporting, it can take [from 12 hours to five days for a person to get results back](https://my.clevelandclinic.org/health/diagnostics/21462-covid-19-and-pcr-testing). And finally, they aren’t cheap at \$100 or more per test. [![Two small white plastic tests with single lines showing negative tests results and a circular depression to place a sample.](https://images.theconversation.com/files/430526/original/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip)](https://images.theconversation.com/files/430526/original/file-20211105-10546-tm86ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip) Rapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests. [Lennardywlee via Wikimedia Commons](https://commons.wikimedia.org/wiki/File:COVID-19_rapid_test.jpg#/media/File:COVID-19_rapid_test.jpg), [CC BY-SA](http://creativecommons.org/licenses/by-sa/4.0/) ## Antigen Tests [Rapid, accurate tests are essential](https://theconversation.com/over-the-counter-rapid-antigen-tests-can-help-slow-the-spread-of-covid-19-heres-how-to-use-them-effectively-166869)to contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results. Antigen tests, the other major type of coronavirus test, while much faster, are less accurate. Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus. To run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that [has antibodies specific to SARS-CoV-2 painted on it in a thin line](https://theconversation.com/antigen-tests-for-covid-19-are-fast-and-easy-and-could-solve-the-coronavirus-testing-problem-despite-being-somewhat-inaccurate-137977). Just like antibodies in your body, the ones on the test strip will [bind to any antigen in the sample](https://labtestsonline.org/tests/covid-19-antigen-test). If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2. Antigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – [even at home](https://theconversation.com/rapid-screening-tests-that-prioritize-speed-over-accuracy-could-be-key-to-ending-the-coronavirus-pandemic-143882). They also produce results quickly, [typically in less than 15 minutes](https://theconversation.com/will-the-new-15-minute-covid-19-test-solve-us-testing-problems-145285). Another benefit is that these tests can be relatively inexpensive at [around \$10-\$15 per test](https://www.cvs.com/shop/home-health-care/home-tests/home-covid-test). Antigen tests do have some drawbacks. Depending on the situation, they can be [less accurate than PCR tests](https://doi.org/10.1093/infdis/jiab337). When a person is symptomatic or has a lot of virus in their system, [antigen tests are very accurate](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7799021/). However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can [miss early cases of COVID-19](https://doi.org/10.1038/d41586-021-00332-4). It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected. ## More Tests, Better Knowledge A few antigen tests are already available over the counter, and on October 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public. At RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used. Understanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you. This post is republished from [The Conversation](https://theconversation.com/us) under a Creative Commons license. Read the [original article](https://theconversation.com/whats-the-difference-between-a-pcr-and-antigen-covid-19-test-a-molecular-biologist-explains-170917). Author Nathaniel Hafer, PhD, is a molecular biologist at UMass Chan Medical School, the academic partner of UMass Memorial Health.
Shard	110 (laksa)
Root Hash	3203128818065089710
Unparsed URL	org,ummhealth!www,/simply-well/the-difference-between-pcr-and-antigen-covid-19-tests s443