Study of Immune Response in Adults and Elderly Subjects Vaccinated With Inactivated Influenza Vaccines

Inclusion Criteria : * Aged 18 to 40 years (adults) or 60 to 85 years (elderly) * Provision of a signed informed consent * Able to attend all scheduled visits and comply with all trial procedures * For a woman of child-bearing potential, avoid becoming pregnant (use of an effective method of contraception or abstinence) for at least 4 weeks prior to vaccination, until 4 weeks after vaccination * Entitlement to national social security. Exclusion Criteria : * For a woman of child-bearing potential, known pregnancy or positive urine pregnancy test * Breast-feeding woman * Participation in another clinical trial investigating a vaccine, drug, medical device or a medical procedure in the 4 weeks preceding the trial vaccination * Planned participation in another clinical trial during the present trial period * Known or suspected 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 * Known systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to the trial vaccine or to a vaccine containing any of the same substances * Chronic illness, at a stage that could interfere with trial conduct or completion, in the opinion of the Investigator * Current alcohol abuse or drug addiction, which may interfere with the subject's ability to comply with trial procedures * Receipt of blood or blood-derived products in the past 3 months, which might interfere with the assessment of immune response * Receipt of any vaccine in the 4 weeks preceding the trial vaccination * Planned receipt of any vaccine in the 4 weeks following the trial vaccination * Known Human Immunodeficiency Virus, Hepatitis B or Hepatitis C seropositivity * Previous vaccination against Influenza in the previous 6 months * Thrombocytopenia, bleeding disorder or anticoagulants in the 3 weeks preceding the inclusion contraindicating IM vaccination * Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent * Febrile illness (oral temperature \>=37.5°C) or moderate or severe acute illness/infection on the day of vaccination, according to investigator judgment