- Antibody tests — sometimes called serology tests — look for antibodies in your blood. Antibodies are proteins your immune system makes to fight off infection. They can take several days or weeks to develop after you've been infected, so the timing of your test is important.
- Antibody tests can be used to determine if you've had COVID-19 in the past, even if you didn't have any symptoms. This can be helpful for understanding the spread of the virus and for determining who may have immunity.
-Antibody tests are not as accurate as PCR tests for diagnosing current COVID-19 infection, and they should not be used for this purpose.
When to get an antibody test
The timing of your antibody test is important. Ideally, you should wait at least 10-14 days after your symptoms began before getting tested. This will give your body time to produce enough antibodies to be detected.
- If you're tested too early, you may get a false negative result. This means that the test result will say you don't have antibodies when you actually do.
Where to get an antibody test
Antibody tests are available at many doctor's offices, urgent care centers, and pharmacies. You can also order an antibody test online from some retailers.
How to interpret your antibody test results
-Antibody test results are typically reported as either positive or negative.
* A positive test result means that you have antibodies to the SARS-CoV-2 virus, which causes COVID-19. This means that you've likely been infected with the virus in the past, even if you didn't have any symptoms.
* A negative test result means that you don't have antibodies to the SARS-CoV-2 virus. This means that you've likely never been infected with the virus, or you were infected too recently for your body to produce antibodies.
Limitations of antibody tests
Antibody tests are not perfect. There is a small chance of getting a false positive or false negative result.
- False positive results: A false positive result means that the test result says you have antibodies when you actually don't. This can happen if you've been infected with a different type of coronavirus, such as the common cold.
- False negative results: A false negative result means that the test result says you don't have antibodies when you actually do. This can happen if you're tested too early after your symptoms began or if your immune system is weak.
Accuracy of Antibody Tests
Antibody tests are not as accurate as PCR tests for detecting current infection with the virus that causes COVID-19. Antibody tests may take several days or weeks to detect the antibodies produced in response to infection with SARS-CoV-2. Antibody tests can be useful to show that a person has been infected in the past, even if they did not have any symptoms, but they are not recommended as the only test for diagnosing current infection.
Antibody tests may be useful for:
- Helping researchers understand how many people have been infected with the virus that causes COVID-19
- Identifying individuals who may have some level of immunity to the virus
- Determining if a person may be eligible to donate blood plasma or convalescent serum containing antibodies to be used to treat the disease in others
