Moderna's COVID-19 vaccine was slightly more effective than Pfizer's at preventing disease and subsequent negative outcomes among U.S. veterans, according to a study published Dec. 1 in The New England Journal of Medicine.
The research team used data from the Veterans Affairs’ healthcare databases. It examined electronic health data for a group of 219,842 veterans who received Pfizer's vaccine and another group of 219,842 who received Moderna's vaccine. Trials were conducted between Jan. 4 and May 14 and between July 1 and Sept. 20.
During a 24-week follow-up period when the alpha variant was prominent, the estimated risk of infection was 5.75 per 1,000 people among the Pfizer group and 4.52 per 1,000 people for the Moderna group. During a 12-week period when the delta variant was prominent, the estimated risk of infection was an additional 6.54 infections per 1,000 people in the Pfizer group.
Compared to Moderna vaccine recipients, Pfizer vaccine recipients had a 27 percent higher risk of infection and a 70 percent higher risk of COVID-19 hospitalization when the alpha variant was prominent. When delta was prominent, the risk of infection was slightly higher for Pfizer vaccine recipients, the study said.