A post-marketing study to evaluate the safety and immunogenicity of a quadrivalent influenza split-virion vaccine in elderly people aged 60 years and older.

Background: Influenza remains a global public health concern. Understanding the vaccination-induced response in an aging population, which is susceptible and at high risk, is essential for disease prevention and control. Here, we report findings on the safety and immunogenicity of a quadrivalent influenza split-virion vaccine (15 µg/subtype/0.