When the FDA issued its guidance for final approval of any Covid-19 vaccine, many estimated that the broad impact of effective Covid vaccines on daily life would not be experienced by most until early 2022. The cascade of factors that led to this view were the FDA guidance that any approved vaccine might only be 50 percent effective, that production and delivery of the vaccine was extremely challenging, and that a significant number of individuals were hesitant to get the vaccine. With the recent reports by two vaccine makers (Pfizer and Moderna) of the results of their preliminary analysis of their Phase 3 trials showing greater than 90 percent protection—and now today’s announcement of a third, AstraZeneca’s, also boasting 90 percent effectiveness—there is cause for more optimism about the timeline for resuming life.
Three factors lead to this new optimism. First, evidence that the vaccine is very likely to be more effective than the FDA’s 50 percent threshold for an approved vaccine will have a direct effect on the spread of infection. The interim analyses were conducted after a predetermined number of participants in their Phase 3 double-blind placebo-controlled trials developed an infection. At that moment, members of the analytic team unblinded the data such that they knew who got the vaccine and who got the placebo. They determined the number of months the vaccine-trial participants had been observed for developing infection; some participants were observed for a few days and others for several months. The analytic team then determined the total months of observation among the placebo participants and determined the same for vaccine participants. Then by comparing the ratio of cases per months of observation in the two groups, the team determined how protective the vaccine was compared with the placebo. The comparisons showed that the vaccines provided exceptional protection.
A second reason for optimism is that there is likely to be a greater acceptance of the vaccine than originally anticipated, due to the high level of protection and few reports of side effects. And the latest surge of the virus, which is currently pressuring hospitals and leading to a significant number of daily deaths nationwide, is necessitating more restrictions—and likely increasing public desire for a vaccine.
The final factor is that the two vaccine makers are applying for emergency use authorization (EUA) based on two months of observation for all participants. If EUA is granted, there should be sufficient doses to vaccinate close to 40 million people in the U.S. starting in late December and early January. And, if the vaccines are offered mainly to frontline workers and those most vulnerable under the EUA, as has been assumed, then hospitalization rates and the death toll could drop significantly before we see widespread immunity and reduction in number of cases among the general population. The reduction in hospitalization and deaths would merit a relaxation of many of the current restrictions sooner.
Early evidence that two vaccines offer high-level protection from Covid and that production has begun on both, and the likelihood that there might be increased acceptance of the vaccine—all raise hopes that we may see a slow and steady reduction in cases and their complications over the next nine months. If it comes to pass, then we might have a more normal Thanksgiving next year.
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