COVID-19 Antibody Test Information
COVID-19 antibody testing is a test that uses a small sample of blood obtained by a finger-prick. Results are ready the same day the sample is obtained. COVID-19 antibody tests are used to determine whether you have had a past infection with SARS-CoV-2, the virus that causes COVID-19. Antibody tests should not be used to diagnose a current COVID-19 infection. It is very important that you are not tested too soon. It can take 2-3 weeks to develop enough antibodies to be detected in an antibody test, with the peak time for testing being 3 or more weeks after infection occurs.
A positive antibody test indicates that the virus is eliminated or being eliminated from the body. Antibodies may be detected in your blood for several months or more after you recover from COVID-19. Although these antibodies probably provide some immunity to the COVID-19 virus, there’s currently not enough evidence to know how long the antibodies last or the level of protection you may have from getting another COVID-19 infection. Though rare, there are some confirmed and suspected cases of reinfection. Studies on COVID-19 antibodies as well as other components of the immune system are ongoing to learn more about immunity.
We encourage you to talk with your healthcare provider about the result you receive in an effort to better understand the condition of your health and as part of your COVID-19 treatment plan.
Antibody testing for COVID-19 may be done if:
- You had symptoms of COVID-19 in the past but you were not tested
- You are about to have a medical procedure done in a hospital or clinic, especially if you have had a positive COVID-19 diagnostic test in the past
- You have had a COVID-19 infection in the past and want to donate plasma, a part of your blood that contains antibodies that can help treat others who have severe cases of COVID-19.
- If a child is sick and the doctor suspects multisystem inflammatory syndrome for children (MIS-C), antibody testing may be ordered to help diagnose MIS-C. Many children with MIS-C have antibodies to COVID-19, indicating past infection with the coronavirus.
If you test positive:
- A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance that a positive result means you have antibodies from an infection with a different virus from the same family of viruses (called coronaviruses). Note: Other coronaviruses cannot produce a positive result on a viral test for SARS-CoV-2.
- Having antibodies to the virus that causes COVID-19 may provide protection from getting infected with the virus again. But even if it does, we do not know how much protection the antibodies may provide or how long this protection may last. Confirmed and suspected cases of reinfection have been reported, but remain rare.
- You may test positive for antibodies even if you have never had symptoms of COVID-19. This can happen if you had an infection without symptoms (asymptomatic).
If you test negative:
- You may never have had COVID-19.
- You could have a current infection or have been recently infected.
- The test may be negative because it typically takes 2-3 weeks after infection for your body to make antibodies. It’s possible you could still get sick if you have been exposed to the virus recently. This means it is possible to still spread the virus.
- Some people may take even longer to develop antibodies, and some people who are infected may not ever develop antibodies.
COVID-19 antibody testing could lead to false-positive or false-negative results:
- False-positive result. The test result is positive, but you actually don’t have antibodies and you did not have an infection in the past. A false-positive result could give you a false sense of security that you’re protected from getting another COVID-19 infection and even with a true positive result, immunity is questionable.
- False-negative result. You have antibodies to the COVID-19 virus, but the test does not detect them. Or you were tested too soon after infection and your body has not had time to develop antibodies. It typically takes 1-3 weeks to develop antibodies after infection, however some people may take even longer to develop antibodies, and some people who are infected may never develop antibodies.
Until researchers are able to provide more information regarding immunity, whether your test results come back positive or negative, please continue to protect yourself and others from the possibility of being infected or reinfected with COVID-19.