October 5’ 2021
With months having passed to the major wave of vaccination in the United States, the scientific community expected to see trends emerge among different groups of vaccinated individuals as well as among recipients of different kinds of vaccine. As the months have gone by, The Center for Disease Control and Prevention have also tried to analyze whether the vaccines remain just as effective in preventing hospitalization months after a recipient receives their shot and the data is finally out.
Data collected from 18 states across the United States between March and August reveal that the Pfizer-BioNTech vaccine prevents hospitalization in 91% of its recipients in the first four months after one receives their second shot. However, the troubling part of the statistic is that the efficacy of the vaccine reduces from 91% to 77% after 120 days have passed. This is especially alarming when put in contrast with the Moderna vaccine which has an initial hospitalization prevention rate of 93% and remains at 92% 120 days post receiving the second shot.
A separate study conducted in late September by the The New England Journal of Medicine, which evaluated the real-world effectiveness of the vaccines at preventing symptomatic illness in about 5,000 health care workers in 25 states, revealed that the Pfizer-BioNTech vaccine had an effectiveness of 88.8 percent, compared with Moderna’s 96.3 percent effectiveness.
The most real consequence that such data has is on the debate of booster shots- when and how often must we start administering them to people that have already been vaccinated with their primary doses? If the Pfizer-BioNTech vaccine drops in efficacy substantially, there are valid reasons for individuals that received the Pfizer vaccine to receive their booster shots sooner than those that received a Moderna vaccine.
However, the scientific community claims there is not much to worry about and that these stats should not alarm people to the degree that they have. “Yes, likely a real difference, probably reflecting what’s in the two vials,” said John Moore, a virologist at Weill Cornell Medicine in New York. “But truly, how much does this difference matter in the real world?” “It’s not appropriate for people who took Pfizer to be freaking out that they got an inferior vaccine”, he adds.
One of the primary reasons why such fears have been labelled unfounded is because the vaccines have remarkably similar efficacy against symptomatic infection. Here, the Pfizer-BioNTech vaccine has an efficacy of 94% while Moderna has an efficacy of 93%. This is also the reason why they have been described as more or less equal since the initial few months of their administration.
The second reason why worry seems unfounded is because initially, scientists had hoped that the vaccines would produce a 50-60% efficacy. When the vaccines far surpassed that expectation, to debate 88.8% versus 96.3% does not seems like a worthwhile cause. The vaccines have, by and large, done significantly better than anyone had expected and prevented a great number of deaths and hospitalizations. Such finer details were bound to emerge only with time and more studies will definitively show how and when booster shots for the vaccines would have to be administered. Till then, however, the government is focussing its efforts on making sure that at the very least, people receive their first doses.