Study Comparing the Immune Response of Fluarix and Fluzone Influenza Vaccines

Inclusion Criteria: * All adults 18 years and older. * Subjects who the investigator believes can and will comply with the requirements of the protocol (e.g., return for follow-up visit and completion of the diary cards) should be enrolled in the study. * Written informed consent obtained from the subject. * If the subject is female, she must be of non-childbearing potential, i.e. either surgically sterilized or one year post-menopausal; or, if of childbearing potential, she must be abstinent or have used adequate contraceptive precautions . Exclusion Criteria: * Use of any investigational or non-registered product (drug or vaccine) within 30 days preceding the administration of the study vaccine, or planned use during the study period. * Has received any other licensed vaccines within 2 weeks (for inactivated vaccines) or 4 weeks (for live vaccines) prior to enrollment in this study. * History of hypersensitivity to a previous dose of influenza vaccine. * History of allergy or reactions likely to be exacerbated by any component of the vaccine(s) including egg, chicken protein, gelatine, formaldehyde, gentamicin sulphate, thimerosal or sodium deoxycholate. * Acute disease at the time of enrollment. (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 diarrhea, mild upper respiratory infection with or without low-grade febrile illness, i.e. Oral temperature \<37.5°C (99.5°F) / Axillary temperature \<37.5°C (99.5°F)). * History of Guillain Barré syndrome within 6 weeks of prior receipt of inactivated influenza virus vaccine. * Pregnancy and lactating females.