The aim of the study is to evaluate the safety and immunogenicity of the 2011-2012 formulation of Fluzone and Fluzone High-Dose vaccines in participants aged 65 years and older.

Objectives:

• To describe the safety of Fluzone vaccine and Fluzone High-Dose vaccine among adults ≥ 65 years of age.
• To describe the immunogenicity of Fluzone vaccine and Fluzone High-Dose vaccine among adults ≥ 65 years of age.

Historically, the annual safety and immunogenicity study of Fluzone vaccine has been conducted in the US in support of licenses held by sanofi pasteur in various countries.

Participants will be randomized to receive a dose of either Fluzone® or Fluzone® High-Dose vaccine and will be followed up for safety and immunogenicity. The duration of participation in the trial will be approximately 1 month.

Inclusion Criteria:

• Subject is ≥ 65 years of age on the day of inclusion.
• Informed consent form (ICF) has been signed and dated.
• Able to attend all scheduled visits and to comply with all trial procedures.

Exclusion Criteria:

• History of serious adverse reaction to any influenza vaccine.
• Receipt of any vaccine within 30 days before receiving study vaccine, or plans to receive another vaccine before the 2nd visit.
• Participation in another interventional clinical trial investigating a vaccine, drug, medical device, or medical procedure in the 30 days preceding the first study vaccination or during the course of the study, unless no intervention for the other study occurred within the 30 days prior to the first study vaccination and none are planned before the subject would complete safety surveillance for the present study.
• Influenza vaccination in the 6 months preceding enrollment in the study.
• Known systemic hypersensitivity to eggs, chicken proteins, latex, or any of the vaccine components, or a history of a life-threatening reaction to Fluzone or Fluzone High-Dose vaccine or to a vaccine containing any of the same substances (the complete list of vaccine components is included in the Investigator's Brochure and/or the package insert) .
• Receipt of immune globulins, blood, or blood-derived products in the past 3 months.
• Thrombocytopenia, which may be a contraindication for intramuscular (IM) vaccination, at the discretion of the Investigator.
• Bleeding disorder or receipt of anticoagulants in the 3 weeks preceding inclusion, which may be a contraindication for IM vaccination, at the discretion of the Investigator.
• 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).
• Chronic illness that, in the opinion of the Investigator, is at a stage where it might interfere with trial conduct or completion.
• Seropositivity for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C, as reported by the subject.
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily.
• Current alcohol or drug addiction that, in the opinion of the Investigator, might interfere with the ability to comply with trial procedures.
• Moderate or severe acute illness/infection (according to Investigator judgment) or febrile illness (temperature ≥ 38.0°C [≥ 100.4°F]) on the day of vaccination. A prospective subject should not be included in the study until the condition has 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.