May 19, 2020
Area(s) of Interest: Public Health
With a growing number of tests claiming to identify people who have been exposed to SARS-CoV-2 and potentially immune to COVID-19, the American Medical Association (AMA) has published guidance to help ensure physicians and the general public are aware of the limitations and potential uses of serological testing, also known as antibody testing.
AMA cautions about using these tests to determine individual immunity and warns that the discontinuation of physical distancing should not be made on the basis of antibody test results. While antibody tests may play an important role in determining the overall prevalence of COVID-19 in the U.S. population, including asymptomatic infection, inherent limitations exist in using them to identify prior infection in individuals.
“Given that we do not yet have scientific evidence showing if, when and for how long individuals might become immune to COVID-19, physicians and the general public should not use antibody testing to consider anyone immune to the disease—doing so may lead individuals to falsely assume they can stop physical distancing and further the spread of illness,” said AMA President Patrice A. Harris, M.D. “Although many are using these tests to determine whether an individual had COVID-19, we encourage physicians to only use antibody tests authorized by the Food and Drug Administration (FDA) and only for the purposes of population-level studies, evaluating recovered individuals for convalescent plasma donations, or along with other clinical information as part of a well-defined testing plan for groups or individuals.”
AMA’s new guidance provides an overview of the current state of antibody testing for SARS-CoV-2, including the limitations, potential uses, and how they are and are not regulated.
Many of the antibody tests currently on the market may return a significant number of false positive results, as well as show cross-reactivity—meaning the tests also identify antibodies for other coronaviruses, such as those causing the common cold. Given these limitations, AMA recommends that currently available antibody tests not be used as the sole basis of diagnosing COVID-19, and not be offered to individuals as a method of determining immune status, and not be used to inform decisions such as returning to work, discontinuing physical distancing, or as the basis for “immunity certificates.”
The California COVID-19 Testing Task Force has also published evaluation criteria for COVID-19 serology screening—both rapid disposable serology tests and enzyme linked immunosorbent assays.