As more tests claim to identify people who have been exposed to the novel coronavirus, potentially making them immune, the AMA issued guidance Thursday to help ensure that physicians and patients know the limitations and potential uses of serological testing, also known as antibody testing. 

The guidance cautions physicians and others about using antibody tests to determine individual immunity to SARS-CoV-2 and warns that the physical distancing should not be discontinued based on antibody test results.
 
“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,” said AMA President Patrice A. Harris, M.D., in a news release. “Doing so may lead individuals to falsely assume they can stop physical distancing and further the spread of illness. 

“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.”
 
The AMA’s new guidance provides an overview of the current state of antibody testing for SARS-CoV-2, including their limitations, potential uses and how they are and are not regulated. This guidance can be found online as part of the AMA’s COVID-19 Resource Center. The Indiana State Department of Health (ISDH) has also cautioned that many antibody tests being marketed have not been scientifically validated.
 
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, the AMA said in the news release. Many antibody tests on the market may return a significant number of false positive results, as well as show cross-reactivity, which means the tests also identify antibodies for other coronaviruses, such as those causing the common cold. 

Given these limitations, the AMA recommends that currently available antibody tests not be used as the sole basis of diagnosing COVID-19; not be offered to patients 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 AMA noted that concerns continue to mount about the performance and fraudulent labeling of many available coronavirus antibody tests. Most of the more than 120 tests on the market have not been authorized by the FDA, despite marketing claims to the contrary. Like ISDH, the AMA urges physicians to pay close attention to the FDA regulatory status of all available SARS-CoV-2 antibody tests. 
 
The new AMA guidance also calls for providing messaging to medically underserved communities and those disproportionately impacted by COVID-19 and whose housing or employment status may make it difficult to adhere to physical distancing recommendations. The messaging should explicitly take into consideration the cultural and social features affecting their ability to make long-term choices on physical distancing and other COVID-19 precautions, the AMA said.