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A COVID Vaccine When?
Don Mosier, MD, PhD | Rimini Road

There has been a global rush to develop a safe and effective vaccine to prevent COVID-19 infection. Russia has already licensed the “Sputnik 5” vaccine despite just announcing results from phase 1 and 2 early trials. Results of the two trials just published in the September 4th issue of the medical journal Lancet showed that two shots with the coronavirus spike protein (critical for infecting humans) expressed by modified adenoviruses induced good immune responses in 76 adult volunteers. But the level of neutralizing antibodies able to prevent coronavirus infection in tissue culture was low raising doubts about whether or not the vaccine would protect recipients. Enrollment in a much larger phase 3 trial in Russia has just begun, so the safety and efficacy of “Sputnik 5” remains to be established. If this were the first and best vaccine to be developed, it is unlikely that it would be distributed in the United States, which has chosen to go it alone in the vaccine race.

There is a political push to announce a vaccine by November, and a stronger scientific pushback that licensing a safe and effective vaccine cannot be rushed. The CEOs of all the companies developing and testing vaccines as well as Francis Collins, the Director of the National Institutes of Health, and Tony Fauci, Director of the National Institute of Allergy and Infectious Diseases, have pledged that no vaccine will be approved until it is proven safe and effective. Each of the two current phase 3 trials in the US have enrolled 30,000 volunteers who are randomly assigned to receive either the vaccine or a placebo. These are double-blind studies, so no one involved in the trials knows who gets the real vaccine and who gets the dummy until the independent data safety monitoring board breaks the code. The trial of the Oxford/AstraZeneca vaccine candidate was halted for one week because one recipient had a serious adverse reaction involving the nervous system. This is not uncommon in large-scale clinical trials, but it does highlight how difficult it is to predict when a treatment or vaccine will be approved. The other US phase 3 trial of the Moderna RNA vaccine is proceeding, but there has never been a licensed vaccine that used this technology, so some scientists are skeptical that this will be the needed breakthrough.

If there were a licensed vaccine ready for distribution late this year, how many people would take it? A recent Gallup poll indicated that one-third of the US population would refuse to get the vaccine shots (all current candidates require 2 shots). That level of population immunity would slow the spread of the virus but would not be high enough to end the pandemic.

While we wait for verified safety and efficacy results from vaccine trials, we must continue the only protective measures that work: wear masks, practice social distancing, wash hands frequently, and use hand sanitizer after touching surfaces with common use.

 

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