Study to Evaluate the Immunogenicity and Safety of an Investigational Influenza (H1N1 Influenza Virus) Vaccine in Adults, Using Two Different Manufacturing Processes

Inclusion Criteria

• All subjects must satisfy ALL the following criteria at study entry:
• A male or female aged 18 to 60 years of age at the time of the first vaccination.
• Subjects who the investigator believes that they can and will comply with the requirements of the protocol.
• Written informed consent obtained from the subject.
• Satisfactory baseline medical assessment by history and physical examination.
• 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 multiple-user device.
• Female subjects of non-childbearing potential may be enrolled in the study. Female subjects of childbearing potential may be enrolled in the study, if the subject 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 (drug or vaccine) other than the study vaccine within 30 days preceding the first dose of the study vaccine or planned use during the study period.
• 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 >= 37.5°C (99.5°F), or acute symptoms greater than "mild" severity on the scheduled date of first vaccination.
• Clinically or virologically confirmed influenza infection within 6 months preceding the study start.
• 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 coumarin derivatives, other vitamin K antagonists 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 acetylsalicylic acid, and without a clinically-apparent bleeding tendency, are eligible.
• Any contraindication to intramuscular administration of the influenza vaccines.
• An acute evolving neurological disorder or history of Guillain-Barré syndrome.
• 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.
• Any conditions which, in the opinion of the investigator, prevents the subjects from participating in the study.