Overview
- New England Journal of Medicine results show a 34.5% relative reduction in laboratory-confirmed influenza with Pfizer’s quadrivalent modRNA vaccine versus a licensed inactivated shot (57 cases vs 87).
- The randomized trial enrolled 18,476 healthy adults ages 18–64 across the United States, South Africa, and the Philippines, comparing the modRNA vaccine with Sanofi’s Fluzone.
- Most confirmed cases were caused by A/H3N2 and A/H1N1, antibody responses were higher for influenza A, and noninferiority criteria were not met for B strains during a season with minimal B circulation.
- Reactogenicity was higher with the mRNA shot (local reactions 70.1% vs 43.1%; systemic events 65.8% vs 48.7%; fever 5.6% vs 1.7%), yet most events were mild or moderate and serious adverse events were similar through six months.
- Pfizer says it is discussing the data with federal regulators without an approval timeline as HHS has canceled nearly $500 million in mRNA vaccine research funding and Moderna has faced FDA requests for more data on its mRNA flu efforts.