Serologic, or antibody, tests identify people who have previously been infected with the COVID-19 virus and do not show whether a person is currently infected.
If someone was infected with COVID-19, there will be antibodies in their blood whether the person ever felt sick or not. The testing measures the body’s immune response to the virus. It does not detect the virus itself. The COVID-19 vaccines could cause you to test positive on some antibody tests. This is because your body develops an immune response when you get vaccinated.
With any test, there is always a risk of incorrect test results – false-positive and false-negative results. We need a good and accurate test we can rely on. The Vermont Department of Health convened a working group of experts to research antibody tests. Their findings conclude that at this time, the serologic (antibody) tests that are currently available would not produce results that are accurate or reliable enough for Vermont. The working group will continue to meet regularly and will be watching closely for changes and improvements in serologic testing. Recommendations may change based on new data.
Though certain providers may offer antibody testing in Vermont, the working group cautions against using serologic testing to make decisions about individuals. For example, the test should not be used to establish “proof of immunity.” However, this type of test could help us better understand the population-level rate of infection from COVID-19 in Vermont.
The CDC is working with commercial laboratories to estimate the percentage of people who were infected with the COVID-19 virus. The strategy involves working with state, local, territorial, academic and commercial partners to better understand COVID-19 in the United States using serology testing for surveillance.
Learn more from the Food and Drug Administration about COVID-19 tests