biostudies-literatureJain VGlaxoSmithKline2578084https://www.ebi.ac.uk/biostudies/studies/S-EPMC12574568biostudies-literatureUnknown21(1)<i>Fluarix Tetra</i> is a quadrivalent seasonal influenza vaccine that has been approved in India for immunization of adults and children aged ≥6 months. This study was conducted in adults aged ≥65 years in India to fulfill a post-approval regulatory commitment. In this prospective, multicenter, single-arm, open-label, Phase 4 study, participants were administered a single 0.5-mL dose of <i>Fluarix Tetra</i> (2023-2024 Northern Hemisphere). The primary objectives were to assess the reactogenicity and safety of <i>Fluarix Tetra</i> by monitoring solicited adverse events (AEs) within 7 days post-vaccination, as well as unsolicited AEs and serious AEs (SAEs) within 21 days post-vaccination. The secondary objective was to evaluate immunogenicity by monitoring the geometric mean titers, geometrHuman vaccines & immunotherapeuticsReactogenicity, safety, and immunogenicity of a quadrivalent seasonal influenza vaccine in adults aged 65 years and older: Phase 4 study results from India during December 2023-February 2024.PMC12574568218702Qian HStruyf FGupta VTatchou ENCauwberghs FJain VBest-Sule KfalseReactogenicity, safety, and immunogenicity of a quadrivalent seasonal influenza vaccine in adults aged 65 years and older: Phase 4 study results from India during December 2023-February 2024.<i>Fluarix Tetra</i> is a quadrivalent seasonal influenza vaccine that has been approved in India for immunization of adults and children aged ≥6 months. This study was conducted in adults aged ≥65 years in India to fulfill a post-approval regulatory commitment. In this prospective, multicenter, single-arm, open-label, Phase 4 study, participants were administered a single 0.5-mL dose of <i>Fluarix Tetra</i> (2023-2024 Northern Hemisphere). The primary objectives were to assess the reactogenicity and safety of <i>Fluarix Tetra</i> by monitoring solicited adverse events (AEs) within 7 days post-vaccination, as well as unsolicited AEs and serious AEs (SAEs) within 21 days post-vaccination. The secondary objective was to evaluate immunogenicity by monitoring the geometric mean titers, geometr2025-01-01T00:00:00Z2025 Dec2026-07-15T06:11:41.18Z2026-06-30T03:16:35.158ZS-EPMC125745684115975710.1080/21645515.2025.2578084