Study of a Single Dose or Two Doses of a Trivalent Inactivated Influenza Vaccine Produced at Shenzhen, China

Inclusion Criteria

• Aged ≥ 6 months on the day of inclusion
• Informed Consent Form has been signed and dated:
• by the parent(s) or legally acceptable representative, if applicable, for subjects <18 years of age. Additionally, an assent form has been signed by the subject if aged 10 to 17 years (based on local regulations).
• by the subject himself/herself for subjects ≥18 years of age.
• Subject and parent(s)/legally acceptable representative (if applicable) are able to attend all scheduled visits and to comply with all trial procedures
• For subjects aged 6-35 months only: Born at full term of pregnancy (≥37 weeks) and with a birth weight ≥2.5 kg
• For subjects aged 3-8 years only: Subject has previously received at least one dose of influenza vaccine in the past years or has a history of prior exposure to influenza virus through natural infection.

Exclusion Criteria

• Subject is pregnant (positive urine pregnancy test), or lactating, or of childbearing potential (to be considered of non-childbearing potential, a female must be pre-menarche or post-menopausal for at least 1 year, surgically sterile, or using an effective method of contraception or abstinence from at least 4 weeks prior to vaccination and until at least 4 weeks after vaccination)
• Participation at the time of study enrollment (or in the 4 weeks preceding the first trial vaccination) or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure
• Receipt of any vaccine or planned receipt of any vaccine within the period from 2 weeks before to 2 weeks after trial vaccination (subjects aged ≥3 years) or within the period from 2 weeks before the first trial vaccination to 2 weeks after the second trial vaccination (subjects aged 6-35 months)
• For subjects aged 6-35 months only: Previous vaccination against influenza (i.e. 2 consecutive doses of influenza vaccine [same seasonal strain composition]) any time prior to study enrollment or history of prior exposure to influenza virus through natural infection
• Vaccination against influenza given in the past 6 months with any influenza vaccine or planned receipt of influenza vaccination during the present study
• Receipt of immune globulins, blood or blood-derived products in the past 3 months, which might interfere with assessment of the immune response
• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
• Reported history of seropositivity for Human Immunodeficiency Virus (HIV), after questioning the subject or the subject's parents or another legally acceptable representative
• Known systemic hypersensitivity to eggs, chicken proteins, neomycin, formaldehyde and octoxynol-9, or to any of the vaccine components, or history of a life-threatening reaction to the vaccine used in the study or to a vaccine containing any of the same substance
• Self-reported thrombocytopenia, as reported by the subject, parent or legally acceptable representative contraindicating intramuscular vaccination
• Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular vaccination upon investigator's judgment
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
• Current alcohol abuse or drug addiction that might interfere with the ability to comply with trial procedures
• Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
• Moderate or severe acute illness/infection (according to investigator judgment) on the day of vaccination or febrile illness (axillary temperature ≥37.1°C). A prosp