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

Inclusion Criteria : * Aged 18 to 60 years on the day of inclusion. * Informed consent form signed. * Able to attend all scheduled visits and to comply with all trial procedures. * For a woman, inability to bear a child or negative urine pregnancy test at the first visit. Exclusion Criteria : * Systemic hypersensitivity to egg proteins, chick proteins, or any of the vaccine components, in particular, neomycin, formaldehyde, and octoxinol 9, or history of a life-threatening reaction to the trial vaccine or a vaccine containing the same substances. * Febrile illness (oral temperature \>= 37.5°C, or rectal equivalent temperature \>= 38.0°C) on the day of inclusion. * Participation in another clinical trial in the 4 weeks preceding the trial vaccination. * Planned participation in another clinical trial during the present trial period. * Congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroids therapy. * Unstable chronic illness (defined as illness requiring hospitalization or a clinically significant change in medication in the 12 weeks prior to inclusion) at a stage that could interfere with trial conduct or completion. * Current abuse of alcohol or drug addiction that may interfere with the subject's ability to comply with trial procedures. * Blood or blood-derived products received in the past 3 months. * Any vaccination in the 4 weeks preceding the trial vaccination. * Vaccination planned in the 4 weeks following the trial vaccination. * Previous vaccination against influenza (in the previous 6 months). * Thrombocytopenia or bleeding disorder contraindicating intramuscular vaccination. * Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent.