My last newsletter mentioned that antibody testing for SARS-COV-2, the virus responsible for COVID-19, would soon be available. In talking to many of you I am aware that some of your friends and family have had an antibody test performed and I have fielded questions as to when my office will start offering a test. I want to update you and pass along information regarding antibody tests that are currently on the market and more accurate tests that are soon to be available. Brian Metzger MD of Austin Infectious Disease Consultants sent a letter to local doctors on behalf of Travis County Medical Society discussing antibody testing. A summary of some of that information follows.
With use of a blood sample, testing can identify antibodies produced against the virus responsible for COVID-19. This test is different from the ones used to diagnose the disease, which are done via a nasal swab, oropharyngeal swab or saliva test. The antibody test will be important for several reasons:
1. To help determine the prevalence of COVID-19 in the population
2. To identify individuals who have had the infection and are immune.
3. To help determine the phase of the infection (recent past vs. distant past infection)
4. To identify individuals who may be candidates to donate plasma which is being used for treatment of COVID-19 patients.
5. Possibly to help with return to work decisions.
This type of testing is currently in development. As of April 16th, the Food and Drug Administration (FDA) has approved only one antibody test to detect this virus and it is not yet on the market. The FDA has allowed unvalidated tests to be sold in the US without undergoing FDA review of data. These are the tests that friends and family may have had and told you about, but they have limitations. The FDA requires these companies to disclose that:
1. The test has not been reviewed by the FDA
2. Negative results do not rule out COVID-19 infection
3. Positive results may be due to past or present infection with other corona virus strains. These are the strains that cause the common cold. So essentially a positive test can’t accurately differentiate between COVID-19 and the common cold.
4. Results from these tests should not be used as the basis to diagnose or exclude past or present COVID-19 infections.
This gives me pause because a false positive test result (a test that shows antibodies to COVID-19 when none actually exist) can give the patient the idea that they are no longer susceptible to the infection, resulting in discontinuation of social distancing and other means of protecting themselves from infection.
In the coming weeks FDA approved tests will become available and will hopefully be more reliable than the tests currently on the market. Until that time, I do not recommend one of the current tests as they lack the reliability needed for this infection.
As always, my office is here to take care of your health care needs whether related to COVID-19 or not.
In Good Health,
Kerry D Rhodes MD & the Rhodes Concierge Care Team