COVID-19 antibody and diagnostic testing

Members should check with their health care provider on when it’s medically appropriate to receive an antibody test. The CDC is the most reliable source for the latest information on antibody testing.

Much has been written on testing related to COVID-19. The following information addresses COVID-19 antibody and diagnostic testing, the purpose of each test and each test’s effectiveness.

Testing for antibodies: Serologic testing detects antibodies the body has created in response to past exposure to COVID-19 (SARS-CoV-2). It measures the body’s immune response and does not detect the virus itself. In the early days of an infection, when the immune response is building, antibodies may not be detected. There is not enough evidence to say that a positive test means the person is immune from re-infection. 

According to the FDA, serological tests can play a critical role in the fight against COVID-19 by helping health care professionals identify individuals who may have been exposed to SARS-CoV-2 virus and may have developed an immune response. In the future, this may potentially be used to help determine, together with other clinical data, whether these individuals are less susceptible to infection.

Public Health officials and provider organizations are learning more about the virus and determining the role of serologic testing in return-to-work policies and other infection prevention protocols.

Testing for infection: Molecular assay (SARS-CoV-2 RNA PCR) is used to diagnose a current infection and looks for the actual genetic information of the virus from a respiratory or nasal swab and is highly accurate.  This testing is not appropriate once the acute infection has passed—no virus will be present to detect.

The FDA regulates the validity and accuracy of lab testing, and they are relaxing the requirement that all test manufacturers submit data to the FDA for review prior to approval. The result is that some SARS-CoV-2 antibody testing products are entering the marketplace without FDA review.

We consider FDA review and approval to be an integral step in determining that lab tests are effective and their results are accurate. Part of meeting a standard of medically necessary care includes thorough validation and review of testing by the appropriate regulatory agency. Given that we are in unprecedented times and face a public health crisis, it is understandable that the FDA has lessened the administrative burden companies face. But this comes with some risks in that companies may make unsubstantiated claims that their tests are FDA approved or authorized, or false claims that their serologic tests can diagnose COVID-19. 

Those companies will ultimately answer to the FDA for false or misleading claims. But in the interim, we are making every effort to validate the safety and efficacy of any serologic testing we offer. 

The SSM Health Lab Methods Evaluation Team is validating one of these serology tests to detect IgG antibodies to SARS-CoV-2, and when the review is completed and it is available, this test will be performed at four centrally located labs in the SSM Health footprint: 

  • SSM Health Saint Louis University Hospital, St. Louis, MO  
  • SSM Health St. Anthony’s Hospital, Oklahoma City, OK 
  • SSM Health St. Mary’s Hospital, Madison, WI  
  • SSM Health St. Mary’s Hospital, Jefferson City, MO