The US Food and Drug Administration (FDA) issued a safety communication reminding the public and healthcare providers that results from currently authorized SARS-CoV-2 antibody tests should not be used to evaluate a person's level of immunity or protection from COVID-19 at any time, and especially after the person received a COVID-19 vaccination.
"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," said Tim Stenzel, M.D., PhD, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA's Center for Devices and Radiological Health in a statement.
According to the FDA safety communication statement, current authorized SARS-CoV-2 antibody tests are not validated to evaluate immunity or protection from COVID-19 infection. The FDA recommends that SARS-CoV-2 antibody tests should be ordered only by health care providers who are familiar with the use and limitations of the test.
The FDA noted that the authorized vaccines for prevention of COVID-19 induce antibodies to specific viral protein targets; post-vaccination antibody test results will be negative in individuals without a history of previous natural infection if the test user does not detect the type of antibodies induced by the vaccine.
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.
The FDA also provided additional information and recommendations to the public and health care providers about the use of antibody tests in people who received a COVID-19 vaccination.
The agency wrote, "The FDA will continue to monitor the use of authorized SARS-CoV-2 antibody tests for purposes other than identifying people with an immune response to SARS-CoV-2 from a recent or prior infection."
The Interim recommendations for use of serologic tests can be found on the CDC website.