Study of a Single Dose or Two Doses of a Quadrivalent Influenza Vaccine in Subjects Aged 6 Months or Older in India

All participants were vaccinated with the QIV (split-virion, inactivated) Northern Hemisphere (NH) or Southern Hemisphere (SH) formulations by the intramuscular (IM) route. Immunogenicity of the vaccine was assessed at baseline (Day 0) and 28 days after the last injection. Safety data were collected up to 28 days after each injection. Serious adverse events (SAEs) were collected throughout the trial.

Inclusion criteria

• Aged 6 months or older on the day of inclusion
• For participants aged 6 to 35 months only: born at full term of pregnancy (>=37 weeks) or birth weight >=2.5 kg or both
• Informed consent form had been signed and dated by the participants / participants' parent(s) or another legally acceptable representative and by an independent witness, if required by local regulations. For participants aged 7 to 17 years of age, assent form has been signed and dated by the participants
• Participants / participants' parent/legally acceptable representative were able to attend all scheduled visits and to comply with all trial procedures

Exclusion criteria

• For participants aged 9 years or older only: participant was pregnant, 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 in the 4 weeks preceding the first trial vaccination or planned receipt of any vaccine in the 4 weeks following any trial vaccination (except Oral Poliomyelitis Vaccine (OPV) received during national immunization days)
• For participants aged 9 years or older only: previous vaccination against influenza (in the previous 9 months) with any influenza vaccine
• For participants aged 6 months to 8 years only: previous priming with any influenza vaccine (i.e., participants who received 2 doses for at least 1 previous influenza season)
• Receipt of immune globulins, blood or blood-derived products in the past 3 months
• 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)
• Self-reported history of seropositivity for Human Immunodeficiency Virus (HIV), Hepatitis B, or Hepatitis C, after questioning
• Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccine used in the trial or to a vaccine containing any of the same substances
• Self-reported thrombocytopenia or as reported by the parent/legally acceptable representative, contraindicating intramuscular vaccination
• Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating IM vaccination
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
• For participants aged 9 years or older only: current alcohol abuse or drug addiction
• Chronic illness that, in the opinion of the Investigator, was 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 >=38.0 degree Celsius). A prospective participants should not be included in the study until the condition had resolved or the febrile event has subsided
• Identified as an Investigator or employee of the Investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (i.e., parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study