The purpose of the study is to obtain immunogenicity and safety data at different dose levels of an investigational H1N1 pandemic influenza vaccine in healthy adults 18 years of age and older.

Inclusion Criteria:

• Subject is 18 to 59 years old (age stratum A) or 60 years of age or older (age stratum B) at the time of screening
• Subject has an understanding of the study, agrees to its provisions, and gives written informed consent prior to study entry
• Subject is generally healthy, as determined by the investigator's clinical judgment through collection of medical history and the performance of a physical examination
• Subject is physically and mentally capable of participating in the study and willing to adhere to study procedures to include completion of all elements of the study diary
• If female of childbearing potential, subject has a negative urine pregnancy test result within 24 hours prior to the scheduled first vaccination and agrees to employ adequate birth control measures for the duration of the study

Exclusion Criteria:

• Subject has participated in another clinical study involving an investigational drug, biological product or device within 30 days prior to study enrollment or is scheduled to participate in another clinical study involving an investigational drug, biological or device during the course of this study
• Subject has a history of exposure to A/H1N1/California/07/2009 virus or a history of vaccination with A/H1N1/California/07/2009 antigen or a closely related influenza virus antigen
• Subject has inherited or acquired immune deficiency
• Subject currently has or has a recent history of significant neurological, cardiovascular or pulmonary (including asthma), hepatic, metabolic, rheumatic, autoimmune, hematological or renal disorder