Influenza Vaccine (Split Virion), Inactivated, Quadrivalent (Shenzhen Kangtai)

Primary objectives: (1) To demonstrate that 28 days after one dose of quadrivalent influenza virus split vaccine was administered to healthy people aged 3 years and above, the seroconversion rate (SCR) and geometric mean titer (GMT) of HI antibodies of the four vaccine types were non-inferior to those of the same type in the control group; (2) To evaluate the SCR and seroprotection rate (SPR) of HI antibodies of the four vaccine types in healthy people under 60 years of age 28 days after one dose of the trial vaccine; (3) To evaluate the SCR and SPR of HI antibodies of the four vaccine types in healthy people aged 60 years and above 28 days after one dose of the trial vaccine. Secondary objectives: (1) To evaluate the immunogenicity of one dose of quadrivalent influenza virus split vaccine in healthy people aged 3 years and above; (2) To evaluate the safety of one dose of quadrivalent influenza virus split vaccine in healthy people aged 3 years and above.

Primary objective: To evaluate the safety of one dose of quadrivalent influenza virus split vaccine in healthy people aged 3 years and above. Secondary objective: To preliminarily evaluate the immunogenicity of one dose of quadrivalent influenza virus split vaccine in healthy people aged 3 years and above.