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Can antibody testing reveal COVID-19 immunity?

We don’t yet know what antibody tests tell us about COVID-19.

In the media and in social media conversation, you may have heard about antibody, or serological, testing. Some people even claim it can show whether a person is still at risk of becoming ill from COVID-19.

Attractive as this sounds, we don’t yet know how effective antibody testing is for COVID-19. That limits the value of this test for now.

Two types of tests for COVID-19 are available.

  • Molecular testing—A nose swab test that measures if the viral genetic material is present. This type of test gives results, which we report as positive cases.
  • Antibody testing—A blood (serum) test to determine if protective antibodies are present. These results are harder to interpret. When a person is infected with the virus that causes COVID-19, typically your body’s defenses fight back and produce antibodies in the blood. These antibodies remain in the blood for some time. Gloved hands hold a vial of blood

It may someday be possible for a blood test to accurately determine if someone was infected with COVID-19 and then has the antibodies present. This type of testing is done with other diseases like measles, where finding antibodies in the blood can show if the person is immune. But, unlike measles, we don’t know how long antibodies to COVID-19 will remain in a person’s blood after infection. If a person has the antibodies, we don’t know if that will prevent them from getting ill.

Scientists are studying COVID-19 to answer these questions. Until we know more, antibody testing can’t predict whether a person can get COVID-19 in the future.

Can antibody testing protect our community?

We shouldn’t base important policy decisions that put the health of our community at risk on uncertain information.

Yes, antibody testing has the potential to help us understand how much risk our community faces from COVID-19 in the future. And it could help us determine if enough people are immune to COVID-19 to prevent another wave of cases.  But because we don’t yet know how long antibodies remain in the blood and the level of protection they provide, this type of testing can’t yet tell us how much of the population is immune.

We can’t yet use this information to determine if COVID-19 will rebound when we lift social distancing restrictions. We can’t yet use this information to determine if someone is protected from this disease if they return to work or school.

How reliable are antibody tests?

Antibody tests for COVID-19 are new, with many different tests arriving on the market. The Food and Drug Administration has authorized very few of these tests through an emergency use authorization process.

Even if the test you receive is FDA authorized, the tests may still yield false results. Because the reliability of these tests is uncertain, it may not be wise to use the results to make decisions like whether to visit an elderly relative or wear personal protective equipment at work.

For now, antibody testing remains an important area of study. It is still not precise enough to support individual or community-level health decisions. As we learn more this may change. Your public health team is following this topic closely and will bring you updates as the science changes.

If you have symptoms like cough or shortness of breath, talk to your medical provider about testing.

Your best means to protect yourself and those around you from COVID-19 is to follow the Stay Home, Stay Healthy order and take other steps like:

  • Wash your hands.
  • Cover your cough.
  • Wear a mask if you can’t maintain social distance.
  • Maintain social distance and avoid unnecessary travel.

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