Evaluate Reactogenicity & Immunogenicity of Adjuvanted Influenza Vaccine in Elderly Adults Previously Vaccinated With the Same Candidate Vaccine. Fluarix™ Administered in Young & Elderly Adults Will be Used as Reference

Since influenza vaccines are normally administered every year because of the frequent change in their antigenic composition, the safety and immunogenicity profiles of the adjuvanted influenza vaccine need to be re-evaluated after repeated vaccine administration. In this study, subjects enrolled in a previous study will receive a booster dose with the 2006-2007 season's formulations of Fluarix or the adjuvanted vaccine.