Can an antibody test be used to diagnose a current COVID-19 infection?

Antibody tests should generally not be used to diagnose a current infection with the virus that causes COVID-19. An antibody test may not show if you have a current infection because it can take 1 to 3 weeks after the infection for your body to make antibodies.

What is antibody testing in the context of COVID-19?

Antibody testing, or serology testing, is a simple blood draw that can help identify if you have been exposed to SARS-CoV-2, the virus that causes the COVID-19 infection, and if you have developed antibodies. Antibodies are proteins in the blood made by the immune system to help fight a viral infection.

Why antibody testing Is not currently recommended to assess immunity after COVID-19 vaccination?

Currently authorized SARS-CoV-2 antibody tests have not been evaluated to assess the level of protection provided by an immune response to COVID-19 vaccination. If antibody test results are interpreted incorrectly, there is a potential risk that people may take fewer precautions against SARS-CoV-2 exposure.

How long after infection with the virus that causes COVID-19 can the antibody test be effective?

After infection with the COVID-19 virus, it can take two to three weeks to develop enough antibodies to be detected in an antibody test, so it's important that you're not tested too soon.

Can a COVID-19 antibody test tell you how much protection you might have?

Test results from currently authorized SARS-CoV-2 antibody tests should not be used to evaluate a person's level of immunity or protection from COVID-19.

COVID-19 and Antibody tests explained: IgM and IgG antibodies to Coronavirus

Can we use COVID-19 antibody tests to evaluate a person’s level of protection after the vaccine?

Currently authorized SARS-CoV-2 antibody tests have not been evaluated to assess the level of protection provided by an immune response to COVID-19 vaccination.If antibody test results are interpreted incorrectly, there is a potential risk that people may take fewer precautions against SARS-CoV-2 exposure. Taking fewer steps to protect against SARS-CoV-2 can increase their risk of SARS-CoV-2 infection and may result in the increased spread of SARS-CoV-2.

What does a positive antibody test result mean for COVID-19?

A: A positive antibody test result could mean you previously had a SARS-CoV-2 infection or COVID-19. A positive antibody test could also mean the test is detecting antibodies in your blood in response to your COVID-19 vaccine.

Do people produce COVID-19 antibodies after infection?

Most people who've recovered from COVID-19 do make antibodies against the virus.

What does a negative COVID-19 antibody test result mean?

A negative result on a SARS-CoV-2 antibody test means antibodies to the virus were not detected in your blood.

It is unknown if all people who have a SARS-CoV-2 infection will develop antibodies in their bodies in an amount that can be detected by a SARS-CoV-2 antibody test.

What does it mean if I have no COVID-19 antibodies in my blood?

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. Antibody testing is not currently recommended to determine if you are immune to COVID-19 following COVID-19 vaccination.

Will a person with COVID-19 vaccine have a positive antibody test?

A COVID-19 vaccination may also cause a positive antibody test result for some but not all antibody tests. You should not interpret the results of your SARS-CoV-2 antibody test as an indication of a specific level of immunity or protection from SARS-CoV-2 infection.

Do I need the COVID-19 vaccine if I still have antibodies?

Yes, the COVID-19 vaccines are recommended, even if you had COVID-19.

Do vaccinated people who got COVID-19 have more COVID-19 antibodies?

Lab research suggests that people with hybrid immunity make higher levels of virus-fighting antibodies than people who've been either vaccinated or infected. Their antibodies are also more potent than those in people who've only gotten their initial COVID-19 vaccines.

What types of COVID-19 tests are available in the US?

Diagnostic tests can show if you have an active COVID-19 infection. Antibody or serology tests look for antibodies in a blood sample to determine if an individual has had a past infection with the virus that causes COVID-19 but cannot be used to diagnose current COVID-19 infection.

What is the difference between antibodies and the vaccine in the context of COVID-19?

While antibodies and vaccines are both viable options to counteract the virus that causes COVID-19, there are major differences. While an antibody may immediately help treat an existing infection, a vaccine will train the immune system to protect against future infections. To learn more about differences between antibodies and vaccines visit Vanderbilt University Medical Center for more information.

Can I return to work after having the COVID-19 antibody test?

Antibody test results should not be used to determine if someone can return to work or school.

Can the COVID-19 antibody test give false negatives?

That’s because it takes a week or two after infection for your immune system to produce antibodies. The reported rate of false negatives is 20%. However, the range of false negatives is from 0% to 30%, depending on the study and when in the course of infection the test is performed.

What does a negative COVID-19 antigen test result mean in asymptomatic persons?

Negative test results using a viral test (NAAT or antigen) in asymptomatic persons with recent known or suspected exposure suggest no current evidence of infection. These results represent a snapshot of the time around specimen collection and could change if tested again in one or more days.

Does a negative COVID-19 rapid antigen test mean I don't have COVID-19?

If you have a negative test, but have symptoms of COVID-19: You may have COVID-19, but tested before the virus was detectable, or you may have another illness, such as the flu.

How long do COVID-19 antibodies last?

At this time, it is unknown for how long antibodies persist following infection and if the presence of antibodies confers protective immunity.

Does your immune system get stronger after COVID-19?

Any time you catch a virus and recover from the illness, you retain antibodies. These antibodies help your body fight off future infections so that you either don't get sick or have milder symptoms.

How long does immunity last after COVID-19?

Because of the limited length of follow-up, it remains unclear how long immune protection will last after previous infection

How does the COVID-19 vaccine boost your immune system?

Vaccines work by stimulating your immune system to produce antibodies, exactly like it would if you were exposed to the disease. After getting vaccinated, you develop immunity to that disease, without having to get the disease first.

What is the difference between the IgM and IgG antibodies tests for COVID-19?

Both SARS-CoV-2 IgM and IgG antibodies may be detected around the same time after infection. However, while IgM is most useful for determining recent infection, it usually becomes undetectable weeks to months following infection; in contrast, IgG is usually detectable for longer periods.

What is the accuracy of the COVID-19 antigen test?

If possible, taking an at-home rapid COVID-19 test the day of the event is ideal. While these tests aren't 100% accurate, a negative result strongly suggests that you're not contagious at that particular time.