A Study of Fluzone® High-Dose Vaccine Compared With Fluzone® Vaccine In Elderly Adults

The aim of this study is to determine the efficacy of Fluzone High-Dose compared to standard dose Fluzone for laboratory-confirmed or culture-confirmed influenza caused by influenza types/subtypes that are similar (for laboratory-confirmed) or antigenically similar (for culture-confirmed) to those contained in the respective annual vaccine formulations.

Primary Objective:

* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to laboratory-confirmed influenza caused by any influenza viral types/subtypes, associated with the occurrence of a protocol-defined influenza-like-illnesses (ILI).

Secondary Objectives:

* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to laboratory-confirmed influenza, caused by any influenza viral types/subtypes, associated with the occurrence of a protocol-defined ILI.
* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to culture-confirmed influenza, caused by any influenza viral types/subtypes, associated with the occurrence of a protocol-defined ILI.
* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to culture-confirmed influenza caused by viral types/subtypes antigenically similar to those contained in the respective annual vaccine formulations, associated with the occurrence of a modified Centers for Disease Control and Prevention (CDC)-defined ILI.
* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to culture-confirmed influenza caused by any influenza viral types/subtypes, associated with the occurrence of a modified CDC-defined ILI.
* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to culture-confirmed influenza caused by viral types/subtypes antigenically similar to those contained in the respective annual vaccine formulations, associated with the occurrence of a respiratory illness.
* To compare the clinical efficacy of Fluzone High-Dose to that of Fluzone in elderly adults, with respect to culture-confirmed influenza caused by any influenza viral types/subtypes, associated with the occurrence of a respiratory illness.

The trial will span 2 influenza seasons. Each study year, participants will be randomized to receive one dose of either Fluzone® High-Dose or Fluzone® vaccine prior to the start of the influenza season and will be followed until the end of each season.

The duration of each participant's participation in the respective study year will be 6 to 8 months, depending on the time of enrollment.

Eligibility Criteria:
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 at the time of study enrollment (or in the 4 weeks preceding the trial vaccination), or planned participation during each year of the trial period, in another clinical trial investigating a vaccine, drug, medical device, or medical procedure (Note: Concomitant participation in an observational trial is acceptable)
* 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 High-Dose or 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 contraindicating intramuscular (IM) vaccination, as judged by the investigator
* Bleeding disorder or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular vaccination, as judged by the investigator
* Current alcohol abuse or drug addiction
* Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
* 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
* Moderate or severe acute illness with or without fever (oral temperature \> 99.0ºF \[\> 37.2ºC\]). If this contraindication exists, vaccination will be deferred until the individual has been medically stable and/or afebrile (temperature ≤ 99.0 ºF \[≤ 37.2ºC\]) for at least 24 hours
* Signs and symptoms of an acute infectious respiratory illness. If this exists, vaccination will be deferred until the symptoms resolve.