SARS-CoV-2 Update on Antibody Testing

This Covid update is more  optimistic than past updates.  The data is changing rapidly and this will change the outlook and recommendations as they become outdated.  Today, I am going to discuss how some studies are suggesting that SARS CoV 2 is much more wide spread than we realized which implies a much lower fatality rate. I also want to share information on antibody testing including, which tests are good and the importance of choosing an accurate test.  

The below graphic is a slide I prepared for a few decision makers on 4/26/20. It evaluates case hospitalization and case fatality rates in LA County vs potential infection hospitalization and fatality rates in LA County.  The difference between case and infection rates are based on studies using antibody testing. The chart and graph evaluate the number of hospitalizations and deaths as of 4/26 relative to the  potential infections based on the multiples from the NY data and the USC study.​

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​In New York City, the rate of cases vs infections presented by Gov. Cuomo was approximately a multiple of 12, suggesting a much lower infection fatality rate. In Los Angeles, USC completed a study using antibody testing suggesting the we had 28-55 times more infections that cases reported. These are in-line with the Stanford/ Santa Clara study suggesting they had 50X more infections that cases reported. All of these studies optimistically show a much lower hospitalization and fatality rate.  Having said that, there are problems with the antibody tests, so we need to evaluate these tests and studies with some healthy skepticism. 

For my patients, I am offering the Quest RT-PCR for active symptoms and the Abbott serology test to evaluate prior exposure.  The Abbott serology test has been tested internally at Abbott and through a separate commercial lab. From internal testing Abbott reports a sensitivity of 100% and a specificity of 99.5%.  The outside lab validated the prior testing suggesting a sensitivity of 100% and a specificity of 99.4%. When evaluating antibody tests, the accuracy is very important as many of these tests are not very accurate.  The specificity of these tests is the more important parameter, as you want as few false positives as possible.

If you are not a patient of mine, but are interested in antibody testing, the FDA has given letters of authorization to some companies.  Click here for a complete list.  [https://www.fda.gov/medical-devices/emergency-situations-medical-devices/emergency-use-authorizations#covid19ivd]

With any of the tests, they should be done in conjunction with a conversation with your doctor.  The antibodies show past exposure.  The antibody seems to offer a window of protection, though there are questions related to seroconversion and the permanence of immunity after developing antibodies.

On a separate note, I wanted to include some educational links to excellent talks on SARS-CoV-2.

The first is by Dr. Olsterholm from the MN Center of Infectious Disease Research and Policy (CIDRAP)  He has 5 excellent podcasts thus far and many webinars available at this site. https://www.cidrap.umn.edu/covid-19/podcasts-webinars

The second excellent educational talk on SARS-CoV-2 is by Dr. Pamela Bjorkman a Cal-tech professor whose lab is currently evaluating the virus.  https://www.youtube.com/watch?v=OBcc_dk9Q9U

Be well,


Amy