COVID-19: Antibody Tests for Everybody?
Antibody tests – also known as serological tests – have the potential to play a crucial role. These tests detect the presence of antibodies in the blood. If antibodies are present, this indicates that the person has been exposed to the virus and has developed antibodies against it, which may mean that the person has at least some immunity to the coronavirus. (Presently, there is considerable debate in the medical community as to how much, if any, immunity a previously-exposed person possesses that will make him or her immune to future exposures to the virus.) In the early days of an infection when the body’s immune response is still building, antibodies may not be detected, so antibody tests are not reliable. But because the results from these tests can help identify those persons who are still at risk in the workplace or in public, the FDA has very recently been focusing on reviewing antibody/serological tests in more depth.
Last month FDA established an Emergency Use Authorization (EUA) process whereby developers can request FDA authorization for antibody/serological tests. To date FDA has only issued four EUAs for such tests, but expects to approve more in the coming weeks. In order to better facilitate the preparation and submission of EUA requests, the Agency just announced that it is developing “EUA Templates”, which will be available in the next few days.
The need for FDA approval of EUAs for antibody/serological tests has become more acute because there have been reports in the scientific literature and in the popular press that several (or perhaps many) antibody tests presently on the market do not work or result in too many false positives or false negatives. Such non-EUA tests have been allowed on the market because FDA decided to use a “regulatory flexibility” policy that allows developers to put serological tests on the market without prior FDA review so long as (1) the tests are validated by the developer to determine that they are accurate and reliable, (2) the developer notifies the FDA that it has validated the tests, and (3) the tests are labeled appropriately including that they are not to be used as a sole basis for diagnosis.
According to the FDA, problems have arisen because some test developers have “misused the serology test kit notification list to falsely claim their serological tests are FDA approved or authorized” and others “have falsely claimed that their tests can diagnose COVID-19.” To remedy the first problem, the Agency is now posting on its website the tests that have been approved by the FDA under EUAs. (The website also includes serological tests that have not been approved under EUAs.) To help remedy the false claims, FDA announced that it is collaborating with the NIH’s National Cancer Institute and the National Institute of Allergy and Infectious Diseases and the CDC to establish a capability at NIH to evaluate serological tests for developers. This effort will include an evaluation of the serology tests already available for use as well as of the tests not yet on the market where additional validation data is needed to support an EUA. In the meantime, FDA is stressing that it expects all antibody/serological tests to be validated as set forth in the original EUA Guidance.
The FDA has just updated its FAQs on Antibody/Serology Tests and these FAQs can be found here.