If the Pfizer and Moderna vaccines prove effective with healthcare workers, who are exposed daily to the coronavirus, that could provide the needed confirmation to convince doubters to get vaccinated.
Radical changes in how we conduct our everyday lives during the COVID-19 pandemic have imposed a unique challenge for establishing the effectiveness of coronavirus vaccines.
When you receive the vaccine you are likely to follow the medical recommendations to continue safety measures. Dr. Anthony Fauci told CNN news anchor Jake Tapper on Nov. 15, 2020, that he would continue wearing a mask after getting vaccinated and recommended that everyone else should do so as well. To emphasize that point Dr. Fauci insisted that "masks and social distancing are here to stay." He added that although a vaccine may be effective "You don't necessarily know for you how effective it is."
But if most of us wisely follow Dr. Fauci's guidelines for safety after inoculation, how will we know what protected us: the vaccine or the safety measures? In fact, we wouldn't know for sure. And that is the problem with the reported high effectiveness ratings of coronavirus vaccines based on the clinical trials.
To test efficacy both Pfizer and Moderna administered their vaccines to one group of volunteers (experimental group) and a placebo to an equal number in another group (control group). The placebo groups showed significantly more instances of infection than the groups that received the vaccine. Based on these findings the two pharmaceutical companies declared their vaccines "effective" -- 94.1% for the Moderna vaccine and 95% for the Pfizer vaccine.
But to accurately evaluate efficacy also requires data on the post-inoculation behavior of the volunteers in the studies, both placebo and vaccine groups. What were their exposures to the virus after inoculations? Only if they are exposed to the virus can we make a valid assessment of the effectiveness of the vaccines.
To understand the importance of this concern about behavior, consider this analogy. If the military provided enhanced protective gear to soldiers and then sent them home for two months, the fact that they then showed no wounds would not establish the effectiveness of the new gear. Only when the soldiers return to the front lines of battle can the efficacy of the gear be assessed.
Similarly, if you are not exposed to the coronavirus how would we know if it was the vaccine that protected you--or would protect you if you were exposed to it?
Another analogy makes that point even more clearly.
Pre-pandemic, when people received shots for the annual flu virus they left their doctor's offices or pharmacies and returned to their usual activities: work, shopping, family gatherings, shaking hands, and other close physical contacts. They attended theaters and movie houses, jammed into packed stadiums, and used public transportation. In other words, their activities gave them extensive opportunities for exposure to the flu.
Let's imagine that a comparable group received a placebo rather than the flu vaccine. They too would be engaging in the same activities that would put them at risk for the flu. If large numbers of the placebo group were infected with the seasonal flu and the vaccine group had few cases, we could reasonably conclude that the vaccine was effective. The crucial factor was that both groups likely had extensive exposure to the virus.
Similar exposure can't be assured for the volunteers in the coronavirus trials after they were inoculated. Even testing for antibodies in the post-inoculation vaccine group would not provide conclusive evidence of efficacy since the vaccine itself produces antibodies.
So how can we know if it was their behavior or the vaccine that protected them?
The importance of that question is underscored by reports of a dramatic drop this year in seasonal flu cases in the U.S. and worldwide that can be traced to the widespread practices of wearing masks, social distancing, and lockdowns for protection against COVID-19. This welcome decline in seasonal flu cases is clearly not due to the efficacy of the flu vaccine.
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