Study to Evaluate the Immune Response and the Safety of Fluarix TM/ Influsplit SSW® 2010/2011 or Pandemrix TM

Inclusion Criteria: * Subjects who the investigator believes can and will comply with the requirements of the protocol. Specific attention should be given to the compliance potential of subjects with suspected or known drug and alcohol abuse. * Subjects who have received one dose of Pandemrix at least 6 month before enrolment, to be enrolled in the Groups A or B OR subjects who have not been previously vaccinated with a vaccine against the pandemic H1N1 strain at all, to be enrolled in group C. * A male or female 18 years and above at the time of enrolment. * Written informed consent obtained from the subject. * Healthy subjects or free of acute aggravation of the health status as established by physical examination before entering into the study. * Female subjects of non-childbearing potential may be enrolled in the study. * Female subjects of childbearing potential may be enrolled in the study. Exclusion Criteria: * Use of any investigational or non-registered product other than the study vaccine within 30 days preceding the dose of study vaccine, or planned use during the study period. * Administration of any influenza vaccine within 6 month prior to vaccination in this study. * Presence of evidence of substance abuse or of neurological or psychiatric diagnoses which, although stable, are deemed by the investigator to render the potential subject unable/unlikely to provide accurate safety reports. * Presence of an axillary temperature ≥ 37.5ºC, or acute symptoms greater than "mild" severity on the scheduled date of first vaccination. * Diagnosed with cancer, or treatment for cancer, within the past 3 years. * Any confirmed or suspected immunosuppressive or immunodeficient condition including history of human immunodeficiency virus (HIV) infection. * Chronic administration of immunosuppressants or other immune modifying drugs within 6 months of study enrolment or planned administration during the study period.. * Any administration of a long-acting immune-modifying drug (within 3 months before study start, or a planned administration during the study period. * Receipt of any immunoglobulins and/or any blood products within 3 months of study enrolment or planned administration of any of these products during the study period. * Any significant disorder of coagulation or treatment with warfarin derivatives or heparin. Persons receiving individual doses of low molecular weight heparin outside of 24 hours prior to vaccination are eligible. Persons receiving prophylactic antiplatelet medications, e.g., low-dose aspirin, and without a clinically-apparent bleeding tendency, are eligible. * An acute evolving neurological disorder or history of Guillain-Barré syndrome. * Clinically or virologically confirmed influenza infection within 6 months preceding the study start. * Administration of any vaccines within 30 days before vaccination. * Any known or suspected allergy to any constituent of influenza vaccines; a history of anaphylactic-type reaction to any constituent of influenza vaccines; or a history of severe adverse reaction to a previous influenza vaccine. * Pregnant or lactating female * Female planning to become pregnant or planning to discontinue contraceptive precautions from study inclusion up to 2 months after completion of the vaccination series. * Any conditions which, in the opinion of the investigator, prevents the subjects from participating in the study.