Antibody tests for COVID-19 have been hyped to prove whether you have been infected with the coronavirus, even if you didn’t know it. But experts advise that even if you test positive for COVID-19 antibodies, you might not be protected.
While cases are on the rise in much of the country, only a small percentage of the population has tested positive for COVID-19. For example, in Allegheny County, where Pittsburgh is located, less than 3 percent of the population has had confirmed COVID-19 cases. In much of the country, a similarly low percentage of people have tested positive.
This means that there’s close to a 50 percent chance that an antibody test would give a false-positive test result, according to Dr. Graham Snyder, the medical director of infection prevention at the University of Pittsburgh Medical Center.
He argues that when the disease is still fairly rare in a community, the chances of a false positive test are high, due to problems with the current antibody tests, or because they identify other coronaviruses instead, like the coronavirus that causes the common cold.
Right now, these antibody tests seem to be better used in research to measure population exposure than to guide individual patient care. In addition to the risk of antibody tests falsely showing you have antibodies, new studies suggest that even if you do become infected with COVID-19, the antibodies you produce to fight and prevent it go away within weeks or months in a large percentage of patients.
People across the country, and many physicians and employers, are pushing for antibody tests to screen people to see if they have already been infected. But at least for now, these tests might not be as helpful as we hoped.