The FDA Just Approved An Antibody Test- Here’s What You Should Know

by Kroger Health Staff

Last Updated: May 6, 2020

As certain countries, cities, and states begin to see stabilizing or falling rates of virus transmission, many are asking the question, “How do we return to normal?” One of the most discussed and debated plans for doing so is widespread testing of the population to determine if prior exposure to (and recovery from) COVID-19 has occurred. For many diseases, the presence of antibodies (“custom” immunity proteins created after having an infection) in an individual’s blood can indicate that this exposure and recovery has occurred. Testing for antibodies for SARS-CoV-2, the virus that causes COVID-19, is being studied extensively by the Centers for Disease Control and Prevention (CDC) and other private companies. Many hope that antibody testing will be the answer, but currently the market has been flooded with tests with unknown accuracy . Here are the top three areas that scientists and researchers are working hard to better understand.
  1. Researchers are working to understand if antibodies actually confer future immunity.
    So, the question is: if you have antibodies to SARS-CoV-2, does this protect you from getting COVID-19? To best understand this challenge, we can consider three fairly well-known human diseases: Varicella-Zoster (chickenpox), Clostridium tetani (tetanus), and Human Immunodeficiency Virus (HIV). While the body creates post-infection antibodies for all three diseases, the clinical course of immunity and resistance varies widely. Once someone has been infected with the chickenpox virus, it is virtually impossible for the infection to occur a second time. For tetanus, immunity is transitory, meaning protection lasts for some time but does not a lifetime, and vaccine regimens require boosters. And finally, individuals who have been infected with HIV typically have large amounts of antibodies in their blood, but these do nothing to clear or resolve the infection. Scientists around the world are rapidly collecting data to understand, for COVID-19, 1) how long antibodies tend to stick around after someone has been infected, 2) if these remaining antibodies are actually able to clear the virus effectively, and 3) what antibody levels would be necessary to support long-term immunity. Surveillance trials are well underway to better understand the relationship between antibody presence and immunity.
  2. Tests in the pipeline are being vetted by government bodies to ensure they are giving highly accurate results.
    No clinical or diagnostic test is perfect, but validation testing can ensure they are consistently accurate, save for a tiny percentage of outlier results. When new tests are developed, they are generally compared to a well-vetted, existing, often more complicated or expensive test to ensure they can deliver a consistently comparable result. This is important because each time a diagnostic test is given, one of three things can occur: (1) the test can correctly tell an infected person they are infected, (2) the test can incorrectly tell an infected person they are not infected, or (3) the test can incorrectly tell a non-infected person that they are infected. The latter two situations are known as false negatives, and false positives, respectively. Currently, the FDA has granted emergency use approval to only a small number of manufactured tests, with higher specificity and sensitivity. A high specificity means that a test almost never gives false positives, and a high sensitivity means a test almost never gives false negatives. Tests with high percentages of both are likely to give a spot-on result nearly every single time. If you are getting an antibody test, make sure it is with one of these FDA approved tests.
  3. Test timing is important, and should be taken into consideration when interpreting results.
    According to the CDC, for most people who have been infected with SARS-CoV-2, it takes at least 1-3 weeks for their bodies to produce antibodies. This timing is important, as it means that those who test for antibodies soon into their course of infection could make the incorrect assumption they were never infected, when in fact they had been infected and just not yet produced antibodies. Conversely, if someone tests early after being infected, but does have antibodies present, they could assume incorrectly that they are not a current COVID-carrier and abandon social distancing practices. Because we cannot rule out that someone with antibodies can still spread the disease, social distancing practices remain important.

The FDA is actively working across all sectors to collect the data needed to quickly and efficiently understand how we can use antibody tests to fight COVID-19 and begin to return to normal. In the meantime, you can view which tests have been given emergency authorization here. Already taken an antibody test? Be sure to check out the CDC’s guidance on how to interpret your results and what to do next.

Disclaimer: The information in this story is accurate as of its publication. However, the situation surrounding COVID-19 is ever-evolving. We are working to keep our stories up-to-date as changes occur, but we also encourage everyone to check news and recommendations from the CDC, WHO, and their local authorities.