Moderna mRNA Flu Vaccine 26.6% Superior in Phase 3 Trial

A Phase 3 clinical trial published in the New England Journal of Medicine has shown that Moderna's experimental trivalent mRNA influenza vaccine, mRNA-1010, reduced PCR-confirmed influenza-like illness by 26.6 percent relative to standard-dose flu vaccines among more than 40,000 adults aged 50 and older. The trial, conducted across 301 sites in 11 Northern Hemisphere countries during the 2024-2025 flu season, reported the primary endpoint in 2.0 percent of mRNA-1010 recipients compared with 2.8 percent of those receiving licensed standard-dose trivalent or quadrivalent vaccines, an absolute reduction of 0.8 percentage points.

The randomized, observer-blind study enrolled 40,703 participants with a mean age of 64 years, 57 percent of whom were women. Researchers defined the primary endpoint as reverse transcriptase-polymerase chain reaction-confirmed influenza A or B illness accompanied by at least one systemic symptom and one respiratory symptom. The relative vaccine efficacy met criteria for superiority, with a 95 percent confidence interval of 16.7 to 35.4 percent and a one-sided P value less than 0.001. Efficacy appeared consistent across subgroups, including age, sex, race,...