GSK Advances mRNA Seasonal Influenza Vaccine to Phase 3 Trial Targeting Both Hemagglutinin and Neuraminidase Antigens After Positive Phase 2 OPTIONS XIII Data
GSK (NYSE: GSK) announced Tuesday September 1, 2026 that its mRNA seasonal influenza vaccine candidate will advance to Phase 3 development in September 2026 following positive Phase 2 immunogenicity data presented at the OPTIONS XIII Conference for the Control of Influenza. The vaccine candidate demonstrated higher immune responses against all influenza strains tested compared to licensed standard-dose and high-dose inactivated flu vaccines in both younger and older adults, and was generally well tolerated. Differentiation: GSK's vaccine is the first mRNA flu candidate to advance to Phase 3 designed to target both hemagglutinin (HA) and neuraminidase (NA), the two primary influenza surface antigens; licensed flu vaccines primarily target HA. Growing evidence suggests dual HA-plus-NA targeting could improve protection, illness severity, and transmission reduction. The FDA granted Fast Track designation in July 2026. The advancement sets up direct Phase 3 competition with Moderna's mNEXSPIKE (approved May 2025) and Pfizer's mRNA flu program, extending the mRNA respiratory-vaccine class beyond COVID-19.