CAMBRIDGE, Mass. — In clinical trials, they both proved extraordinarily efficacious. But in the real world, researchers at the Harvard School of Public Health have found differences between the mRNA vaccines produced by Pfizer and Moderna, with the latter coming out on top when it came to preventing infections and hospitalizations.
The study looked at vaccination data for nearly 440,000 U.S. veterans - half of whom received the Moderna vaccine, half of whom got Pfizer - then tracked how they fared through the Alpha and Delta COVID waves.
During the Alpha surge, the study found Pfizer recipients were 27% more likely to get infected than Moderna recipients and 70% more likely to require hospitalization. The case rates for each were 5.75 per 1,000 for Pfizer compared with 4.52 per 1,000 for Moderna.
“I’m not convinced that one of these mRNA vaccines is clearly worse or better than the other,” said Dr. Lindsey Baden, who served as co-principal investigator for Moderna’s vaccine trials last year. “I think what’s most important is to get vaccinated so we prevent severe illness.”
And Baden said that’s exactly what the two vaccines are doing.
“To me, the biggest success of these vaccines -- a year ago here at Brigham and Women’s we would have 200 in-patients with COVID, now we have 20,” he said.
Baden said he wouldn’t let the data from this study guide a choice of a booster shot, most especially if that guidance would mean a delay in getting one.
“Get boosted,” he said. “I think get boosted The most important thing is to get the added protection. And trying to say one of the mRNA vaccines is better than the other to the point where you delay receiving the booster? I’m not convinced that makes sense. I think getting boosted and augmenting your immunity as quickly as possible makes the most sense.”
That may be especially true now that the Omicron variant has been officially detected in the U.S.
“Right now the assessments are ongoing rapidly to determine if vaccine-elicited immune responses -- antibodies -- significantly neutralize Omicron,” Baden said. “Studies are ongoing so it is difficult to have a science-based answer. However, given how the immune responses have worked for Alpha, Beta and Delta, the earlier variants of concern, it’s highly likely that the immunity the current vaccines bring out are protective or at least partially or significantly protective against these new variants.”
>>>MORE: Coronavirus: First case of omicron variant discovered in US
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