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

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.