A Study of the Immunogenicity and Safety of the 2006-2007 Influenza Vaccine

Inclusion Criteria: * Aged at least 18 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 Visit 1 * For a woman of child-bearing potential: use of an effective method of contraception or abstinence for at least four weeks prior to vaccination and at least three weeks after vaccination. Exclusion Criteria: * Febrile illness (oral temperature \>=37.5°C) on the day of vaccination * Breast-feeding * Participation in another clinical trial in the four 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 six months, or long-term systemic corticosteroids therapy * Systemic hypersensitivity to egg proteins, chick proteins, or to any of the vaccine components, or history of a life-threatening reaction to the trial vaccine or a vaccine containing the same substances * Chronic illness 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 three months * Any vaccination in the four weeks preceding the trial vaccination * Vaccination planned in the three weeks following the trial vaccination * Vaccination against influenza in the previous six 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