A Study of the Safety and Immunogenicity of High-Dose Quadrivalent Influenza Vaccine in Subjects Aged 65 Years and Older

The aim of the study is to assess the safety and immunogenicity of two formulations of the high-dose quadrivalent influenza vaccine compared to the licensed high-dose trivalent influenza vaccine control in healthy elderly subjects aged 65 years of age and above. Primary objectives: * To describe the safety profile of all subjects in each study group. * To demonstrate that the high-dose quadrivalent influenza vaccine induces an immune response (as assessed by HAI geometric mean titers (GMTs) that is non-inferior to responses induced by the licensed high-dose trivalent influenza vaccine for the 3 common virus strains at 28 days post-vaccination. Secondary objectives: * To describe post-vaccination immunogenicity for the 4 virus strains (as assessed by seroconversion and seroprotection) for subjects who receive the high-dose quadrivalent influenza vaccine and the licensed high-dose trivalent influenza vaccine. * To describe post-vaccination immunogenicity for the 4 virus strains (as assessed by GMTs, seroconversion, and seroprotection) for subjects who receive the high-dose quadrivalent influenza vaccine and the investigational high-dose trivalent influenza vaccine.