Overview

• The randomized, observer-blind P304 trial enrolled 40,805 adults across 11 countries and followed participants for a median of six months.
• mRNA-1010 delivered 26.6% higher relative vaccine efficacy than a standard-dose flu shot in adults aged 50 and older and a 27.4% gain in those aged 65 and above.
• The vaccine demonstrated strain-specific rVEs of 29.6% against A/H1N1, 22.2% against A/H3N2 and 29.1% against B/Victoria lineages.
• Reported adverse reactions were mostly mild—chiefly injection site pain, fatigue, headache and myalgia—with no increase in serious adverse events.
• Moderna plans to present full Phase 3 data at an upcoming medical conference and to file for regulatory approval before the 2025–2026 flu season.