The main objective of the study is to assess the immune response to a non-adjuvanted H5N1 influenza vaccine in an adult population when administered according to a single prime-boost schedule.

Inclusion Criteria:

Male and female subjects will be eligible for participation in this study if they:

• are 18 to 59 years of age, inclusive, on the day of screening
• have an understanding of the study and its procedures, agree to its provisions, and give written informed consent prior to study entry
• are generally healthy, as determined by the investigator's clinical judgment through collection of medical history and performance of a physical examination
• are physically and mentally capable of participating in the study and follow its procedures
• agree to keep a daily record of symptoms for the duration of the study
• if female of childbearing potential: have a negative urine pregnancy test result within 24 hours prior to the scheduled first vaccination and agree to employ adequate birth control measures for the duration of the study

Exclusion Criteria:

Subjects will be excluded from participation in this study if they:

• have a history of exposure to H5N1 virus or a history of vaccination with an H5N1 influenza vaccine
• are at high risk of contracting H5N1 influenza infection (e.g. poultry workers)
• currently have or have a history of a significant neurological, cardiovascular, pulmonary (including asthma), hepatic, metabolic, rheumatic, autoimmune, hematological or renal disorder
• have any inherited or acquired immunodeficiency
• have a disease or are currently undergoing a form of treatment or were undergoing a form of treatment within 30 days prior to study entry that can be expected to influence immune response. Such treatment includes, but is not limited to, systemic or high dose inhaled (> 800µg/day of beclomethasone dipropionate or equivalent) corticosteroids, radiation treatment or other immunosuppressive or cytotoxic drugs
• have a history of severe allergic reactions or anaphylaxis
• have a rash, dermatological condition or tattoos which may interfere with injection site reaction rating
• have received any blood products or immunoglobulins within 90 days prior to study entry
• have donated blood or plasma within 30 days prior to study entry
• have received any live vaccine within 4 weeks or inactivated vaccine within 2 weeks prior to vaccination in this study
• have a functional or surgical asplenia
• have a known or suspected problem with alcohol or drug abuse
• were administered an investigational drug within 6 weeks prior to study entry or are concurrently participating in a clinical study that includes the administration of an investigational product
• are a member of the team conducting this study or are in a dependent relationship with one of the study team members. Dependent relationships include close relatives (i.e., children, partner/spouse, siblings, parents) as well as employees of the investigator or site personnel conducting the study
• if female: are pregnant or lactating