A Study of Influenza Virus Vaccines in Children and Adults

Inclusion Criteria : * Subject is ≥ 6 months to \< 5 years of age or 18 years of age or older on the day of inclusion. * Parent/legal guardian (if the subject is ≥ 6 months to \< 5 years of age) or adult subject (if 18 years of age or older) is willing and able to attend scheduled visits and to comply with the study procedures during the entire duration of the study. * Subject in reasonably good health as assessed by the Investigator. * Parent/legal guardian (if the subject is ≥ 6 months to \< 5 years of age) or adult subject (if 18 years of age or older) is willing and able to give informed consent. * For subjects ≥ 6 months to \< 5 years of age: subject was born at full term of pregnancy (≥ 37 weeks) with a birth weight ≥ 2.5 kg (5.5 lbs). * For a woman, inability to bear a child or negative serum/urine pregnancy test, if applicable. Exclusion Criteria : For all subjects: * History of allergy to egg proteins, chicken proteins, or one of the constituents of the vaccine, such as thimerosal or formaldehyde. * History of serious adverse reaction to any influenza vaccine. * Laboratory-confirmed influenza infection or vaccination against influenza in the six months preceding enrollment in the study. * Any vaccination scheduled between Visit 1 and Visit 2 or Visit 3. * Participation in any other interventional drug or vaccine trial during participation in this study. * Thrombocytopenia or bleeding disorder contraindicating intramuscular vaccination. * Any condition that in the opinion of the Investigator would pose a health risk to the subject if enrolled or could interfere with the evaluation of the vaccine. * Prior personal history of Guillain-Barré syndrome. For subjects \> 6 months to \< 5 years of age: * Known or suspected impairment of immunologic function or receipt of immunosuppressive therapy or immunoglobulin since birth. * Personal or immediate family history of congenital immune deficiency. * Developmental delay, neurologic disorder, or seizure disorder. * Chronic medical, congenital, or developmental disorder. * Known HIV-positive mother. For subjects 18 years of age and older: * Immunocompromising condition; immunosuppressive therapy (including systemic steroid use for two weeks or more); cancer chemotherapy or radiation therapy at the time of enrollment, planned during the period of this study, or at any time within the past six months. * Diabetes mellitus requiring pharmacological control. * Person deprived of freedom by an administrative or court order (having legal or medical guardian). * For women of childbearing potential, a positive urine pregnancy test, breast feeding, or not using a medically approved and reliable form of contraception (oral contraceptives or double barrier method) for the duration of the trial. * Current use of alcohol or recreational drugs that may interfere with the subject's ability to comply with trial procedures. * Any subject with the following conditions is not eligible for enrollment. However, the subject may be enrolled subsequently if the condition has resolved and enrollment is still ongoing and the subject meets all other inclusion/exclusion criteria: * An acute illness with or without fever in the 72 hours preceding enrollment in the trial. * Clinically significant findings in vital signs or review of systems (Investigator judgment). * Received any vaccinations within the preceding 14 days. * Participation in any other interventional clinical trial within 30 days prior to enrollment. * Receipt of blood or blood products within the three months preceding enrollment in the study.