A Study to Demonstrate the Efficacy of GSK Biologicals' Influenza Vaccine in Adults

Inclusion Criteria: * A male or female age between 18 and 64 years at the time of the first vaccination. * non-childbearing female Exclusion Criteria: * Use of non-registered products * Pregnancy * Hypersensitivity to a previous dose of influenza vaccine * Acute disease at the time of enrolment/vaccination. * History of allergy or reactions likely to be exacerbated by any component of the vaccine * Administration of any other influenza vaccine for the season 2006-2007 * Chronic disorders of the pulmonary or cardiovascular system, including asthma. * Administration of immune-modifying drugs * Administration of immunoglobulins and/or any blood products * History of requiring regular medical follow-up or hospitalization during the preceding year because of chronic metabolic diseases (including diabetes mellitus), renal dysfunction, hemoglobinopathies, asthma or immunosuppression (including immunosuppression caused by medications or by human immunodeficiency virus)