No safety concerns, study terminated due to lack of primary endpoint cases in 2009-2010 Flu season (coincided with H1N1 Pandemic) Subjects followed per-protocol

The aim of this study is to determine the efficacy of Fluzone High Dose vaccine and that of Fluzone® vaccine in the elderly.

Primary objective:

To measure the efficacy of the vaccine, defined as the prevention of laboratory-confirmed influenza caused by viral types/subtypes that are antigenically similar to those contained in the respective annual vaccine formulations.

Secondary objectives:

• To compare the clinical efficacy of Fluzone High Dose vaccine with that of Fluzone® vaccine in elderly adults, with respect to laboratory-confirmed influenza illness caused by any type or subtype of influenza virus.
• To compare the clinical efficacy of Fluzone High Dose vaccine with that of Fluzone® vaccine in elderly adults, in preventing culture-confirmed influenza illness caused by viral types/subtypes antigenically similar to those contained in the respective annual vaccine formulations.

The occurrence of influenza-like illness (ILI) will be determined in elderly participants vaccinated with either Fluzone High Dose or Fluzone® vaccine.

The presence of influenza virus in the respiratory tract of vaccinated individuals with ILI will be confirmed by two methods.

Inclusion Criteria :

• Aged ≥ 65 years on the day of vaccination
• Informed consent form signed and dated.
• Able to attend all scheduled visits and to comply with all trial procedures.

Exclusion Criteria :

• Participation in another interventional clinical trial investigating a vaccine, drug, medical device, herbal supplement, or a medical procedure in the 4 weeks preceding the trial vaccination or planned participation in another clinical trial investigating a vaccine, drug, medical device, herbal supplement, or a medical procedure during each year of participation in the study trial.
• Vaccination against influenza in the 6 months preceding the trial vaccination.
• Systemic hypersensitivity to eggs, chicken proteins, or any of the vaccine components, or a history of a life-threatening reaction to Fluzone vaccine or to a vaccine containing any of the same substances.
• Personal history of Guillain-Barré syndrome.
• Dementia or any other cognitive condition at a stage that could interfere with following the trial procedures.
• Thrombocytopenia, bleeding disorder, or anticoagulation therapy contraindicating intramuscular (IM) vaccination.
• Known or suspected human immunodeficiency virus (HIV), Hepatitis B surface antigen (HBsAg), or Hepatitis C seropositivity.
• Alcohol abuse or drug addiction that could interfere with the subject's ability to comply with trial procedures.
• Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent.
• Bedridden subjects.