Immunogenicity and Safety Study to Evaluate Different Formulations of GSK Biologicals' Influenza Vaccine GSK576389A

In order to find the formulation leading to a maximal increase of the immune response while maintaining an acceptable safety profile, this study is designed to evaluate the immunogenicity, safety and reactogenicity of the different formulations of GSK Biologicals' influenza vaccine administered in adults aged 65 years and older compared to Fluarix.

There are 10 parallel groups: 9 observer blinded groups with subjects 65 years and older receiving an investigational vaccine or Fluarix, and 1 open group with subjects between 18 and 40 years old receiving Fluarix. CMI response will be determined for a subset only.

The Protocol Posting has been updated in order to comply with the FDA Amendment Act, Sep 2007.

Eligibility Criteria:
Inclusion Criteria:

* Subjects who the investigator believes that they can and will comply with the requirements of the protocol should be enrolled in the study.
* A male or female aged 18-40 years old or 65 years or older at the time of the vaccination.
* Written informed consent obtained from the subject.
* Free of an acute aggravation of the health status as established by clinical evaluation (medical history and medical history directed examination) before entering into the study.
* If the subject is female, she must be of non-childbearing potential or if she is of childbearing potential, she must practice adequate contraception for 30 days prior to vaccination, have a negative pregnancy test and continue such precautions for 2 months after completion of the vaccination series.

Exclusion Criteria:

* Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine(s) within 30 days prior to vaccination, or planned use during the study period.
* Administration of other licensed vaccines within 2 weeks (for inactivated vaccines) or 4 weeks (for live vaccines) prior to enrolment in this study.
* Planned administration of a vaccine not foreseen by the study protocol during the entire study period.
* Planned administration of an influenza vaccine other than the study vaccines during the entire study period.
* Vaccination against influenza since January 2007 (with 2007/2008 or 2006/2007 influenza vaccine).
* Administration of more than 14 days of immunosuppressants or other immune-modifying drugs within 6 months prior to the administration of the study vaccine.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination
* Hypersensitivity to a previous dose of influenza vaccine.
* Allergy to any component of the vaccine.
* Acute (active) clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality.
* Acute disease at the time of enrolment. (Acute disease is defined as the presence of a moderate or severe illness with or without fever. All vaccines can be administered to persons with a minor illness such as diarrhoea, mild upper respiratory infection with or without low-grade febrile illness, i.e. axillary temperature\<37.5ºC (99.5ºF).
* Administration of immunoglobulins and/or any blood products within the three months preceding the first administration of the study vaccine or planned administration during the study.
* Any medical conditions in which IM injections are contraindicated.
* Lactating female or female planning to become pregnant or to discontinue contraceptive precautions