From preventing infection to reducing hospitalization and death risks, a groundbreaking analysis compares the real-world effectiveness of the Moderna (mRNA-1273) and Pfizer-BioNTech (BNT162b2) vaccines. Drawing on U.S. veterans' electronic health records, researchers provide the first direct head-to-head evaluation.
Initial randomized trials showed messenger RNA vaccines' impressive efficacy: 95% for Pfizer-BioNTech (BNT162b2) and 94% for Moderna (mRNA-1273). Real-world observational studies confirmed these results. Yet, direct comparisons between the two were missing—until now.
Both target the spike protein but differ in mRNA dose (100µg for Moderna vs. 30µg for Pfizer-BioNTech), dosing interval (four weeks vs. three weeks), and lipid nanoparticle composition. These variations may explain Moderna's stronger antibody response observed in prior studies. But do these translate to better clinical outcomes? This study evaluates both vaccines in the same population.
Researchers examined U.S. veterans vaccinated from January to May 2021, with 219,842 participants per group. During this period, the Alpha variant dominated.
Published in the New England Journal of Medicine, the study confirms both vaccines remain highly effective against infection, hospitalization, and death. However, Moderna showed a slight advantage, with lower risks of infection and hospitalization for Alpha and Delta variants.
Over 24 weeks, documented infection risk was 5.75 events per 1,000 in the Pfizer-BioNTech group vs. 4.52 per 1,000 for Moderna—equating to 1.23 additional cases per 1,000 with Pfizer-BioNTech.
Pfizer-BioNTech also showed modestly higher rates of symptomatic cases (+0.44 per 1,000), hospitalizations, ICU admissions (+0.10 per 1,000), and deaths (+0.02 per 1,000).
Despite these differences, both vaccines are recommended equally when choice is available, per the researchers. Harvard epidemiologist Dr. Barbra A. Dickerman, co-author, notes: "While absolute differences are small, they matter at population scale" and can inform policy decisions.
