While antibody tests may play an important role in determining the overall prevalence of COVID-19 in the U.S. population, inherent limitations exist in using them to identify prior infection in individuals, the American Medical Association said. (andrei_r/GettyImages)
The AMA issued guidance this week to help physicians understand the potential uses and limitations of serological testing, also called antibody testing.
COVID-19 antibody test results should not be used to determine individual immunity and public health decisions, such as discontinuation of physical distancing, the AMA said.
“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 Harris, M.D., in a statement.
“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,” Harris said.
The AMA’s new guidance provides physicians and the general public with 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.
Antibodies can be found in the blood of those who are tested after infection and typically show that a recovered individual has developed an immune response to the virus.
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, according to the AMA.
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, the AMA recommends 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.
AMA also cautions doctors against using these tests to inform decisions in consultation with patients such as returning to work, discontinuing physical distancing or as the basis for “immunity certificates.”
Concerns continue to mount about the performance and fraudulent labeling of many of the SARS-CoV-2 antibody tests currently available, the AMA said.
“The vast majority of more than 120 tests on the market have not been authorized by the FDA, despite marketing claims to the contrary,” the organization said.
A list of all antibody tests authorized by the FDA for SARS-CoV-2 can be found on FDA’s website.
Doctors need to be well versed in the limitations of serology tests and have a strong understanding of both the tests and the potential results. This is particularly true for those caring for marginalized and minoritized patient communities that are disproportionately impacted by COVID-19, where access to testing services may be limited or where housing or employment status of patients may make it difficult for them to adhere to physical distancing and other COVID-19 guidance precautions, the AMA said.