SILVER SPRINGS, Md. (News Nation) — The U.S. Food and Drug Administration Friday authorized the first two COVID-19 serology tests that show an estimated quantity of antibodies present in a patient’s blood, according to a release from the agency.
The FDA cautioned against using the serology test results as an indication of immunity or that a person can stop taking steps to protect themselves and others.
The tests detect antibodies that the immune system develops in response to the SARS-CoV-2 infection–not the virus itself–and should not be used to diagnose an active infection, the FDA noted.
The two tests, both from Siemens, are what are known as “semi-quantative” tests, meaning they don’t display a precise measurement of the antibodies but estimate the quanitities present in the individual’s blood.
“Being able to measure a patient’s relative level of antibodies in response to a previous SARS-CoV-2 infection may be useful as we continue to learn more about the virus and what the existence of antibodies may mean,” said Tim Stenzel, M.D., Ph.D., director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health in the release from the agency. “There are still many unknowns about what the presence of SARS-CoV-2 antibodies may tell us about potential immunity, but today’s authorizations give us additional tools to evaluate those antibodies as we continue to research and study this virus. Patients should not interpret results as telling them they are immune, or have any level of immunity, from the virus.”
Johns Hopkins reports many individual states and employers are initiating antibody studies, called “serosurveys,” but notes without leadership coordinating them, we don’t get as much value from this data.
Widespread serosurveys “would give the best estimate of how coronavirus has hit different populations,” University of Chicago associate professor of ecology and evolution Sarah Cobey, Ph.D., told News Nation, referencing a study published in the JAMA medical journal in late July that estimated the actual number of coronavirus infections was six to 24 times higher than the number of confirmed cases. As of Friday afternoon, there have been more than 4.5 million coronavirus cases confirmed in the U.S. according to the Johns Hopkins COVID-19 map.
“The serosurveys are surveys, they’re like a poll in a presidential election so there’s a margin of error that we need to do repeated serosurveys to know what’s going on. It’s an evolving science,” said U.C. Irvine associate professor of population health and disease prevention Andrew Noymer, Ph.D.
Johns Hopkins says widespread, coordinated serosurveys would provide accurate data on the prevalence of COVID-19; however, they haven’t been conducted widely across the U.S. in a coordinated manner.