After an early hands-off approach, the FDA is taking a more active role in the validation and review of COVID-19 serology tests as they become a key element in some reopening plans. In recent weeks, dozens of serology tests have appeared in the US market; questions are arising over their quality (only four have received FDA approval), according to a report in The New York Times. Even if high-quality tests become ubiquitous, their utility could ultimately vary by state.
Serology tests measure the level of antibodies against a certain pathogen in individuals, in this case, SARS-CoV-2, the virus that causes COVID-19. The presence of antibodies means that the individual has already been exposed to the virus and could be immune should subsequent exposure occur. As states and employers consider reopening plans, serology tests could play a critical role to determine which individuals may still be at risk of infection.
HRI impact analysis
On Saturday, the FDA outlined its plans to expand access to serology tests and identify “well-performing tests.” “Given the active dialogue about serological tests that are currently on the market, and their significance in the nation’s response efforts, we’d like to provide further details about our thinking on these tests and our approach to making accurate and reliable serology tests widely available,” FDA Commissioner Stephen Hahn wrote in a memo announcing the agency’s plans.
The FDA has granted Emergency Use Authorizations (EUAs) to just four tests, but has reported that over 70 tests are on the market based on the agency’s March guidance in which it said it would allow laboratories to self-verify and market serology tests.
With the FDA’s latest policy, it is collaborating with the National Cancer Institute (NCI), the National Institute of Allergy and Infectious Diseases (NIAID) and the CDC to evaluate serological tests for developers.
In the meantime, the FDA issued a letter to healthcare providers recommending that physicians continue to use serological tests but “be aware of their limitations.”
As the FDA works to bring more uniformity and accuracy to serology tests, the challenge of available but unvalidated tests will be compounded by the incidence rate of the virus.
According to the FDA, the positive predictive value of a test may be higher in a region with widespread infection than it would be in an area with only a small number of cases.