Covid 19 Update Aug 28, 2020
This past 10 days there have been two recommendations which have generated considerable discussion in the medical community. First off, the FDA issued an emergency use authorization for convalescent serum to treat Covid 19 infections. Convalescent serum is made from the antibodies of patients who have recovered from Covid 19. The theory is that by transfusing these antibodies patients will have a better chance of recovery. While the therapy appears safe, the data on its effectiveness is unclear. The therapy has NOT been compared to a placebo, so it is impossible to know if it truly helps, or if people would have recovered without it. Convalescent serum has been available for several months, so the hoopla surrounding the announcement was confusing. The emergency use authorization makes the therapy more available yet may also limit the ability of researchers to study it fully. Mayo Clinic has been leading this research with over 30,000 cases, and Tucson Medical Center is part of a network of hospitals that work with Mayo.
Similarly, the CDC issued a new recommendation to not test people who have been exposed to Covid 19 if they do not have symptoms. This recommendation is controversial as many public health officials believe more testing is the only way to truly know the prevalence of the disease in the population. The concern is that barriers may once again be placed in getting testing.
However, just yesterday a new type of test received emergency use authorization. This test can be done in an office and results are available within 20 minutes. It is like an over the counter pregnancy test with the results being one or two lines on the testing card. It reportedly will be priced around $5 a test. Unfortunately, it has a relatively high false negative rate, meaning the person may still have Covid 19 despite testing negative. This detail will limit its usefulness for screening, yet it may help us confirm if someone does have the infection if they are having symptoms. I am not certain if similar tests which may be more accurate will become available from different manufacturers.
While there are several vaccines being looked at throughout the world, I want to highlight a few which may have more promise. As I have mentioned before, the Moderna vaccine is in phase 3 trials with some testing occurring here in Tucson. In addition, there is the Oxford/Astra Zeneca vaccine which is already in phase 3 trials in Europe and will be starting testing here in the US soon. Pfizer and Johnson and Johnson are also working on vaccines which are far along. In Latin America and the Middle East, a Chinese vaccine is in phase 3 trials. Finally, the Russians have approved Sputnik V vaccine for use in their country, yet they decided to skip phase 3 trials and go straight to approval.
The Sputnik vaccine is a good example of political pressure getting ahead of science. If the lethality rate of Covid 19 was high (say 5% or more) then I believe you could justify making that decision. However, with a lethality rate of 1% or less, I strongly feel you must wait to demonstrate the safety and effectiveness of a vaccine. For instance, back in 1990, there was a study published looking at an experimental Coronavirus vaccine for cats which showed that the cats who got the vaccine died at a higher rate when exposed to the virus then those who did not. (Please note this coronavirus was different then Covid 19). In 1976, the US rushed a Swine flu vaccine which resulted in a significant number of cases of a potentially life-threatening condition called Guillen Barre Syndrome. Hence the reason for caution.
Finally, the number of new Covid19 cases here in Arizona continues to decline. We are now averaging less than 600 new cases a day. Deaths are lower as well, with approximately 35 a day on average over the past 7 days. Likewise, the percentage of tests which are positive has declined down to 5% for the past 2 weeks, which is good news.
Take care and have a good week.
Jeff Mayer, MD