Study to Evaluate Immunogenicity and Safety of an Investigational Influenza Vaccine (H1N1)

Inclusion Criteria:

• Japanese male and female adults 20 to 64 years of age at time of the first vaccination, inclusive.
• Good general health as assessed by medical history and physical examination
• Subjects who the investigator believes that they can and will comply with the requirements of the protocol.
• Written informed consent obtained from the subject.
• Access to a consistent means of telephone contact, which may be either in the home or at the workplace, land line or mobile, but NOT a pay phone or other multiple-user device.
• Females of non-childbearing potential may be enrolled in the study.
• Female of childbearing potential may be enrolled in the study, if she:
• has practiced adequate contraception for 30 days prior to vaccination, and
• has a negative pregnancy test on the day of vaccination, and
• has agreed to continue adequate contraception during the entire treatment period and for 2 months after completion of the vaccination series.

Exclusion Criteria:

• Use of any investigational or non-registered product other than the study vaccine(s) within 30 days preceding the first dose of study vaccine, or planned use during the study period.
• History of previous administration of a novel [H1N1]v vaccine.
• Previous participation in study NCT00742885.
• Presence of significant acute or chronic, uncontrolled medical or psychiatric illness.
• Presence or 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 >= 37.5 °C, or acute symptoms greater than "mild" severity on the scheduled date of first vaccination.
• Diagnosed with cancer, or treatment for cancer within 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.
• 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.
• An acute evolving neurological disorder or history of Guillain-Barré syndrome.
• Administration of any vaccines within 30 days before vaccination or planned administration within the first vaccination up to blood sampling at Day 42 and within 30 days prior to blood sampling at Day 182, with the exception of seasonal influenza vaccine.
• Administration of any seasonal influenza vaccine within 14 days before vaccination on Day 0, or planned administration within the first vaccination up to blood sampling at Day 42 and within 14 days prior to blood sampling at Day 182.
• Any known or suspected allergy to any constituent of influenza vaccines or component used in the manufacturing process of the study vaccine; a history of anaphylactic-type reaction to any constituent of influenza vaccines; or a history of severe adverse reaction to a previous influenza vaccine.
• Known pregnancy or a positive urine test result prior to the time of first vaccination.
• Lactating or nursing female.
• Excessive underweight (Body Mass Index [BMI] < 18.5) or excessive obesity (BMI >= 30).
• Any conditions which, in the opinion of the investigator, prevents the subjects from participating in the study.
• Clinically or virologically confirmed influenza infection within 6 months preceding the study start.