Study of Quadrivalent Influenza Vaccine Among Children

The aim of the study is to evaluate a prototype quadrivalent influenza vaccine (QIV), the licensed 2010-2011 trivalent influenza vaccine (TIV) containing the primary B strain (B1), and the investigational TIV containing the alternate B (B2) strain in children.

Primary Objective:

To demonstrate non-inferiority of antibody responses to QIV compared with licensed 2010-2011 TIV (containing the primary B strain) and investigational TIV (containing the alternate B strain) as assessed by geometric mean titer (GMT) ratios for each of the four virus strains separately among children aged 6 months to less than 9 years of age

Secondary Objective:

To demonstrate superiority of antibody responses to each B strain in QIV compared with antibody titers following vaccination with the TIV that does not contain the corresponding B strain, as assessed by GMT ratios and seroconversion rates.

Observational Objective:

To describe the safety profile of QIV among subjects 6 months to less than 9 years of age, as assessed by solicited injection site and systemic adverse events (AEs) collected for 7 days post-vaccination, unsolicited adverse events collected from 21 days post-vaccination, and adverse events of special interest and serious adverse events (SAEs) collected from Visit 1 to Visit 2.

Participants will receive a single dose of their assigned vaccine during Visit 1. For those requiring two doses of influenza vaccine, as per Advisory Committee on Immunization Practices (ACIP) guidance, a second dose of the assigned vaccine will be administered at Visit 2. All participants will be followed up for safety (up to 6 months post final vaccination) and for immunogenicity up to Day 28 post-vaccination (Visit 2 or Visit 3, as appropriate).

Eligibility Criteria:
Inclusion Criteria:

* Subject is 6 months to \< 9 years of age on the day of inclusion.
* Parent/guardian is willing and able to attend scheduled visits and to comply with the study procedures during the entire duration of the study.
* Subject is in reasonably good health as assessed by the Investigator.
* Informed consent is granted by the parent(s) or other legally acceptable representative; assent by subjects 7 to \< 9 years of age.
* For subjects 6 months to \< 24 months of age, born at full term of pregnancy (≥ 37 weeks) and with a birth weight ≥ 2.5 kg (5.5 lbs).

Exclusion Criteria:

* History of allergy to egg proteins or any constituents of the vaccine.
* History of serious adverse reaction to any influenza vaccine.
* Any vaccination scheduled between Visit 1 and Visit 2 (or Visit 1 and Visit 3 for those requiring two doses).
* Receipt of any vaccine in the 4 weeks preceding the first study vaccination.
* Participation in another interventional clinical trial investigating a vaccine, drug, medical device, or medical procedure in the 4 weeks preceding the first study vaccination or during the course of the study.
* Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, 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.
* Personal history of Guillain-Barré syndrome.
* 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).
* Personal or immediate family history of congenital immune deficiency.
* Personal developmental delay, neurologic disorder, or seizure disorder.
* Any chronic illness that, in the opinion of the Investigator, is not well controlled and may interfere with trial conduct or completion, or with assessment of adverse events.
* Known seropositivity for human immunodeficiency virus, hepatitis B, or hepatitis C.
* Receipt of blood or blood-derived products (including immunoglobulin therapy) in the past 3 months, which might interfere with assessment of the immune response.
* Employees of the Investigator or study center, with direct involvement in the proposed study or other studies under the direction of that Investigator or study center, as well as family members of the employees or the Investigator.