I've heard about antibody testing for COVID-19. What is antibody testing? Is it the same as testing to diagnose COVID-19?

Answer From Daniel C. DeSimone, M.D.

Antibody testing shows whether you have antibodies to the virus that causes COVID-19, also called coronavirus disease 2019.

Having antibodies suggests you've either had an infection with the virus in the past or you've had the COVID-19 vaccine. Antibody testing is not used to diagnose COVID-19.

What are antibodies and why are antibody tests done?

Antibodies are proteins. The body makes antibodies when there are things in the body that shouldn't be there, such as viruses. The antibodies help clear out the virus. Having antibodies to a virus may give some protection from the disease caused by the virus for a time.

A blood test can show whether you have antibodies to the COVID-19 virus within days to weeks of having the infection or the vaccine. But antibody testing, also called serology testing, is not done routinely.

A healthcare professional might use an antibody test to diagnose complications of COVID-19. These include multisystem inflammatory syndrome, a rare condition linked to COVID-19.

If you've gotten over COVID-19, you might be able to help others who have COVID-19. If testing shows that you have a high level of antibodies, you might donate part of your blood called plasma. This is called convalescent plasma. It may help others with severe disease who have a weakened immune system.

What tests are used to diagnose COVID-19?

Two types of tests can help diagnose COVID-19.

  • Molecular tests. These tests look for genetic material from the COVID-19 virus.

    Polymerase chain reaction tests, shortened to PCR tests, are molecular tests. You may also hear this type of test called an NAAT test, short for nucleic acid amplification test.

    PCR tests are more accurate than the other type of COVID-19 test, called an antigen test. You can do PCR tests at home. But they are more likely to be done by a healthcare professional and processed in a lab.

  • Antigen tests. These tests look for viral proteins called antigens.

    Antigen tests also may be called rapid COVID-19 tests or at-home COVID-19 tests. These tests are useful if you need quick results.

    Antigen tests are accurate. But they're less accurate than PCR tests. If you have symptoms and an antigen test is negative for COVID-19, take another antigen test after 48 hours to get the best result.

    If you don't have symptoms and get a negative result, test again after 48 hours. If the result is still negative and you think you have COVID-19, you can test a third time after another 48 hours. Or you can get a molecular test or call your healthcare professional.

How do I get a COVID-19 diagnostic test?

In the United States, at-home COVID-19 tests are available from several sources. Free tests can be mailed to U.S. addresses, or you can buy tests in stores and pharmacies or online. The U.S. Food and Drug Administration (FDA) approves the tests. On the FDA website, you can find a list of the tests that are validated and when they expire.

With

Daniel C. DeSimone, M.D.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

May 14, 2024 See more Expert Answers

See also

  1. Antibiotics: Are you misusing them?
  2. COVID-19 and vitamin D
  3. Convalescent plasma therapy
  4. Coronavirus disease 2019 (COVID-19)
  5. COVID-19: How can I protect myself?
  6. Cough
  7. Herd immunity and respiratory illness
  8. COVID-19 and pets
  9. COVID-19 and your mental health
  10. COVID-19 antibody testing
  11. COVID-19, cold, allergies and the flu
  12. COVID-19 tests
  13. COVID-19 drugs: Are there any that work?
  14. COVID-19 in babies and children
  15. Coronavirus infection by race
  16. COVID-19 travel advice
  17. COVID-19 vaccine: Should I reschedule my mammogram?
  18. COVID-19 vaccines for kids: What you need to know
  19. COVID-19 vaccines
  20. COVID-19 variant
  21. COVID-19 vs. flu: Similarities and differences
  22. COVID-19: Who's at higher risk of serious symptoms?
  23. Debunking coronavirus myths
  24. Diarrhea
  25. Different COVID-19 vaccines
  26. Extracorporeal membrane oxygenation (ECMO)
  27. Fever
  28. Fever: First aid
  29. Fever treatment: Quick guide to treating a fever
  30. Fight coronavirus (COVID-19) transmission at home
  31. Honey: An effective cough remedy?
  32. How to measure your respiratory rate
  33. How to take your pulse
  34. How to take your temperature
  35. How well do face masks protect against COVID-19?
  36. Is hydroxychloroquine a treatment for COVID-19?
  37. Long-term effects of COVID-19
  38. Loss of smell
  39. Mayo Clinic Minute: You're washing your hands all wrong
  40. Mayo Clinic Minute: How dirty are common surfaces?
  41. Multisystem inflammatory syndrome in children (MIS-C)
  42. Nausea and vomiting
  43. Pregnancy and COVID-19
  44. Red eye
  45. Safe outdoor activities during the COVID-19 pandemic
  46. Safety tips for attending school during COVID-19
  47. Sex and COVID-19
  48. Shortness of breath
  49. Thermometers: Understand the options
  50. Treating COVID-19 at home
  51. Unusual symptoms of coronavirus
  52. Vaccine guidance from Mayo Clinic
  53. Watery eyes