A phase 3 randomized trial of 8,015 adults aged 50 and older tested mRNA-1083, Moderna's investigational combination mRNA vaccine targeting both seasonal influenza (all four strains) and SARS-CoV-2 (Omicron XBB.1.5). Participants received either mRNA-1083 plus placebo or standard-care coadministered influenza and COVID-19 vaccines. mRNA-1083 met all noninferiority criteria and surpassed comparators: it outperformed standard-dose flu vaccine across all four strains (ages 50–64), high-dose flu vaccine on three of four strains (ages 65+), and bested mRNA-1273 for SARS-CoV-2 responses in both age groups. Solicited adverse reactions were slightly more frequent with mRNA-1083 but were mostly mild-to-moderate and short-lived. No new safety signals emerged.
