As a result of the safety and immunogenicity data generated from earlier dose-ranging studies, the present formulation has been selected for further development in the elderly.

Primary Objective:

To compare the immunogenicity in subjects receiving investigational Fluzone with those of subjects receiving standard Fluzone®.

Secondary Objectives:

Immunogenicity:

To describe the immunogenicity in subjects receiving investigational Fluzone and standard Fluzone®.

Safety:

To evaluate and describe the safety profile of investigational Fluzone in terms of solicited- and unsolicited adverse events and serious adverse events post-vaccination.

Inclusion Criteria:

• Aged ≥ 65 years on the day of vaccination.
• Informed consent form signed.
• Medically stable (Subjects may have underlying illnesses such as hypertension, diabetes, ischemic heart disease, congestive cardiac disorders or hypothyroidism, as long as their symptoms/signs are controlled).
• Able to attend all scheduled visits and to comply with all trial procedures.

Exclusion Criteria:

• Systemic hypersensitivity to eggs, chicken proteins, or any of the vaccine components, or a history of a life-threatening reaction to the standard-dose Fluzone® vaccine or a vaccine containing the same substances (the list of vaccine components is included in the Investigator's Brochure).
• Congenital or history of acquired immunodeficiency, or immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months.
• Systemic corticosteroid therapy as follows:
• Continuous use with a dosage equivalent to > 15 mg/day of oral prednisone for 90 days preceding vaccination
• Sporadic use with a dose of > 40 mg/day of oral prednisone for > 14 days in the 90 days preceding vaccination.

Note: Use of topical or inhalant corticosteroids is acceptable.

• Neoplastic disease or any hematologic malignancy (except localized skin or prostate cancer that is stable at the time of vaccination in the absence of therapy, as well as subjects who have a history of neoplastic disease and who have been disease-free for ≥ 5 years).
• Current abuse of alcohol or drug addiction that may interfere with the subject's ability to comply with trial procedures.
• Receipt of blood or blood-derived products in the past 3 months.
• Vaccination against influenza in the past 6 months.
• Any vaccination in the 4 weeks preceding the trial vaccination.
• Vaccination planned in the 4 weeks following the trial vaccination.
• Participation in another clinical trial in the 4 weeks preceding trial vaccination.
• Planned participation in another clinical trial during the present trial period. Concomitant participation in an observational trial (not involving drugs, vaccines, or medical devices) is acceptable.
• Chronic illness at a stage that could interfere with trial conduct or completion.
• Known current HIV, hepatitis B (HBsAg) or hepatitis C infection or seropositivity.
• Known thrombocytopenia or bleeding disorder contraindicating IM vaccination.
• Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent.
• Acute illness and febrile illness with a temperature ≥ 38.0°C [or 100.4°F]) 72 hours before or on the day of inclusion.
• Received antibiotics therapy within 72 hours preceding the trial vaccination.
• Received any allergy shots in the 7-day period preceding trial vaccination and/or scheduled to receive any allergy shots in the 7-day period after trial vaccination.
• Any condition, which in the opinion of the investigator would pose a health risk to the participant.