Immunogenicity and Safety Study of an Inactivated Influenza Vaccine (Split Virus, Vero Cell Derived) in Adults Aged 50 Years and Older

The purpose of this study is to demonstrate the effectiveness (seroprotection and seroconversion as measured by the hemagglutination inhibition \[HI\] assay) of an investigational Vero cell-derived, trivalent, seasonal influenza vaccine in adults 50 years of age and older. Subjects will be randomized in a double-blind fashion to receive a single intramuscular injection of either the investigational vaccine or a licensed egg-derived seasonal influenza vaccine. Blood will be drawn from all subjects for a determination of HI antibody titers on Days 0 and 21, body temperature and injection site reactions will be monitored daily for 7 days. In addition, subjects will be monitored for adverse events and rises in body temperature until Day 21 and again until Day 180.


Eligibility Criteria:
Inclusion Criteria:

* Are 50 years of age or older on the day of screening
* Have an understanding of the study, agree to its provisions, have the ability to adhere to the provisions of the study and give written informed consent prior to study entry
* If female and capable of bearing children,have a negative urine pregnancy test result within 24 hours prior to the vaccination on Study Day 0 and agree to employ adequate birth control measures.

Exclusion Criteria:

* History of severe allergic reaction or anaphylaxis to egg protein or any other component of the Vero cell-derived influenza vaccine or the egg-derived influenza vaccine
* Oral temperature of \>= 99.5°F (37.5°C) on the day of vaccination in this study (Note: Subjects meeting this exclusion criterion may be rescheduled for vaccination and study entry at a later date if certain requirements \[in the study protocol\] are met)
* Rash or dermatologic condition or tattoos which may interfere with injection site reaction rating
* Blood transfusion or immunoglobulins received within 90 days of study entry
* Live vaccine received within 4 weeks or inactivated vaccine or subunit vaccine received within 2 weeks of study entry
* Previous vaccination against influenza for the 2008/2009 northern hemisphere influenza season
* Functional or surgical asplenia (e.g. from a history of hemoglobinopathies, leukemias, or lymphomas)
* Diagnosed immunodeficiency as a result of a pathological condition
* Pharmacologically induced immunodeficiency as a result of prescribed administration of corticosteroids (e.g., any systemic administration of corticosteroids or an inhaled dose equivalent to 800 mg of beclomethasone dipropionate) or chemotherapeutics or as a result of radiation therapy or any other modality capable of altering normal immunologic response
* Known or suspected problem with drug or alcohol abuse
* Investigational drug received within 6 weeks prior to study entry or concurrent participating in a clinical study that includes the administration of an investigational product
* Subjects who are a member of the team conducting this study or are in a dependent relationship with the study investigator. Dependent relationships include close relatives (i.e., children, spouse/partner, siblings, parents) as well as employees of the investigator.