Moderna submitted an application and data for a booster, but as featureless noted studies showed its efficacy after two doses didn't degrade like Pfizer.
It was a constant refrain from federal health officials after the coronavirus vaccines were authorized: These shots are all equally effective.
That has turned out not to be true.
Roughly 221 million doses of the Pfizer-BioNTech vaccine have been dispensed thus far in the United States, compared with about 150 million doses of Moderna’s vaccine. In a half-dozen studies published over the past few weeks, Moderna’s vaccine appeared to be more protective than the Pfizer-BioNTech vaccine in the months after immunization.
The latest such study, published on Wednesday in The New England Journal of Medicine, evaluated the real-world effectiveness of the vaccines at preventing symptomatic illness in about 5,000 health care workers in 25 states. The study found that the Pfizer-BioNTech vaccine had an effectiveness of 88.8 percent, compared with Moderna’s 96.3 percent.
Research published on Friday by the Centers for Disease Control and Prevention found that the efficacy of the Pfizer-BioNTech vaccine against hospitalization fell from 91 percent to 77 percent after a four-month period following the second shot. The Moderna vaccine showed no decline over the same period.
The two vaccines have diverged more sharply in their efficacy against infection. Protection from both waned over time, particularly after the arrival of the Delta variant, but the Pfizer-BioNTech vaccine’s values fell lower. In two of the recent studies, the Moderna vaccine did better at preventing illness by more than 30 percentage points.
A few studies found that the levels of antibodies produced by the Pfizer-BioNTech vaccine were one-third to one-half those produced by the Moderna vaccine. Yet that decrease is trivial, Dr. Moore said: For comparison, there is a more than 100-fold difference in the antibody levels among healthy individuals.
Still, other experts said that the corpus of evidence pointed to a disparity that would be worth exploring, at least in people who respond weakly to vaccines, including older adults and immunocompromised people.
“At the end of the day, I do think there are subtle but real differences between Moderna and Pfizer,” Dr. Jeffrey Wilson, an immunologist and physician at the University of Virginia in Charlottesville who was a co-author of one such study, published in JAMA Network Open this month. “In high-risk populations, it might be relevant. It’d be good if people took a close look.”
“Pfizer is a big hammer,” Dr. Wilson added, but “Moderna is a sledgehammer.”
Several factors might underlie the divergence. The vaccines differ in their dosing and in the time between the first and second doses. Vaccine manufacturers would typically have enough time to test a range of doses before choosing one — and they have done such testing for their trials of the coronavirus vaccine in children. But in the midst of a pandemic last year, the companies had to guess at the optimal dose. Pfizer went with 30 micrograms, Moderna with 100.
Moderna’s vaccine relies on a lipid nanoparticle that can deliver the larger dose. And the first and second shots of that vaccine are staggered by four weeks, compared with three for the Pfizer-BioNTech vaccine.
The extra week may give immune cells more time to proliferate before the second dose, said Dr. Paul Burton, Moderna’s chief medical officer. “We need to keep studying this and to do more research, but I think it’s plausible.”
Moderna’s team recently showed that a half dose of the vaccine still sent antibody levels soaring. Based on those data, the company asked the F.D.A. this month to authorize 50 micrograms, the half dose, as a booster shot.
https://www.nytimes.com/2021/09/22/heal ... cines.html
Those of us who were vaccinated early last year had no choice of vaccine, we took what was offered to us.
"Everyone is entitled to their own opinion, but not their own facts." - Daniel Patrick Moynihan