Study of Shenzhen Quadrivalent Inactivated Influenza Vaccine Versus the Shenzhen Trivalent Inactivated Influenza Vaccine in Chinese Subjects From 6 Months of Age

The primary objectives of the study were: * To demonstrate the non-inferiority of the immune response in terms of geometric mean titers (GMTs) and seroconversion rates of the SP Shz QIV compared with the SP Shz TIV containing the Victoria lineage strain (TIV1) and the SP Shz TIV containing the Yamagata lineage strain (TIV2) for each strain * To describe the safety profile of each dosage of SP Shz QIV, TIV1 or TIV2 The secondary objectives of the study were: * Group 1 (subjects 6-35 months): To demonstrate the superiority of the immune response of SP Shz QIV compared to TIV2 or TIV1 group after the last dose; demonstrate the superiority of the immune response of the 0.5 mL dose of SP Shz QIV compared to 0.25 mL dose of SP Shz QIV group after the last dose; describe the immune response after administration of the last dose of either SP Shz QIV or SP Shz TIV1 or SP Shz TIV2. * Groups 2 through 5 (subjects ≥ 3 years): To demonstrate the superiority of the immune response of SP Shz QIV compared to TIV2 or TIV1 group after a single dose; describe the immune response after each and every dose for all subjects ≥ 3 years of either SP Shz QIV or SP Shz TIV1 or SP Shz TIV2 * Group 2 (subjects 3 to 8 years), previously unvaccinated ,receiving SP Shz QIV: To describe the immune response after administration of each dose of SP Shz QIV, first dose and second dose of SP Shz QIV respectively * Group 5 (subjects ≥ 65 years only): To assess the compliance, in terms of immunogenicity, of SP Shz QIV with the requirements of the CHMP NfG CPMP/BWP/214/96 in subjects aged 65 years or older. * To describe the safety profile of SP Shz QIV 0.5 mL after each dose.