Antibody Testing Not Useful to Prove Immunity Among Vaccinated: FDA 

Damian McNamara

May 19, 2021

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The US Food and Drug Administration (FDA) is against antibody testing for SARS-CoV-2 testing to determine immunity or protection from COVID-19, especially among those who are vaccinated.

More a reminder than a new policy, the FDA advised against using the antibody test results for these indications in a Safety Communication announced today.

"The FDA is reminding the public of the limitations of COVID-19 antibody, or serology, testing and providing additional recommendations about the use of antibody tests in people who received a COVID-19 vaccination," Tim Stenzel, MD, PhD, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA's Center for Devices and Radiological Health, said in a statement.

"Antibody tests can play an important role in identifying individuals who may have been exposed to the SARS-CoV-2 virus and may have developed an adaptive immune response," he added. "However, antibody tests should not be used at this time to determine immunity or protection against COVID-19 at any time, and especially after a person has received a COVID-19 vaccination."

Not all antibodies are created equal. The agency explained that antibodies from prior SARS-CoV-2 infection differ from antibodies induced by the COVID-19 vaccines. Therefore, testing for prior infection antibodies would not identify people with antibody protection from immunization.

SARS-CoV-2 antibody tests should be ordered only by healthcare professionals who are familiar with the use and limitations of the test, the agency notes.

"The FDA will continue to monitor the use of authorized SARS-CoV-2 antibody tests for purposes other than identifying people with an adaptive immune response to SARS-CoV-2 from a recent or prior infection," Stenzel said.

Damian McNamara is a staff journalist based in Miami. He covers a wide range of medical specialties, including infectious diseases, gastroenterology and critical care. Follow Damian on Twitter:  @MedReporter.

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