Lot-to-Lot Consistency Study of the Investigational, Inactivated, Split-Virion Influenza Vaccine in Adults

The primary objective of this trial is to demonstrate the equivalence, in terms of immunogenicity, of three different industrial lots of the investigational vaccine thereby supporting consistency of the manufacturing process.

Secondary Objectives:

Immunogenicity

To demonstrate that the investigational vaccine induces an immune response at least as good as the one induced by the reference vaccine, in terms of antibody titers.

To assess the immunogenicity of the investigational vaccine using parameters defined in the European Medicines Agency (EMEA) Note for Guidance (CPMP/BWP/214/96).

Safety:

To demonstrate that the investigational vaccine is at least as well tolerated as the reference vaccine, in terms of defined safety profile.

To describe the safety profile after vaccination.

Comfort of the vaccination assessment:

To assess the pain immediately after the injection using a Verbal Rating Scale. To describe the vaccination comfort after the injection using a -Patient-Reported Outcome questionnaire: the Vaccination Comfort Questionnaire.