Test for Past Infection

Decisions about testing are made by state or localexternal icon health departments or healthcare professionals.

Antibody tests for COVID-19 are available through healthcare professionals and laboratories. Check with your healthcare professional to see if they offer antibody tests and whether you should get one.

What do your results mean?

If you test positive

• A positive antibody test result shows you may have antibodies from a previous infection or from vaccination for the virus that causes COVID-19.
• Some antibodies made for the virus that causes COVID-19 provide protection from getting infected. CDC is evaluating antibody protection and how long protection from antibodies might last. Cases of reinfection and infection after vaccination have been reported, but remain rare. But getting vaccinated, even if you have already had COVID-19, can help your body make more of these antibodies.
• You may test positive for antibodies even if you have never had symptoms of COVID-19 or have not yet received a COVID-19 vaccine. This can happen if you had an infection without symptoms, which is called an asymptomatic infection.
• Sometimes a person can test positive for SARS-CoV-2 antibodies when they do not actually have those specific antibodies. This is called a false positive.
• Talk with your healthcare professional about your test result and the type of test you took to understand what your result means. Your healthcare professional may suggest you take a second type of antibody test to see if the first test was accurate.

If you test negative

• You may not have COVID-19 antibodies. This could be because you have not had an infection with the virus that causes COVID-19 or have not received a COVID-19 vaccine.
• Some antibody tests will only detect antibodies from infection, not from vaccination with the virus that causes COVID-19.
• You could have a current infection, been recently infected, or been recently vaccinated. It typically takes 1 to 3 weeks after infection or vaccination for your body to make antibodies. If you are infected, you may get sick and spread the virus before you develop antibodies.
  • Some people may take even longer to develop antibodies, and a small portion of people who are infected or vaccinated may never develop antibodies.
• Sometimes people test negative for SARS-CoV-2 antibodies when they have those specific antibodies. This is called a false negative.
• Talk with your healthcare professional about your test result and the type of test you took to understand what your result means.

If you have symptoms of COVID-19, you should get a viral test to detect a current infection, even if you were previously infected or vaccinated.

Until we know more, continue to take steps including getting vaccinated to protect yourself and others.

Learn more about using antibody tests to look for past infection.

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