The purpose of this study is to assess the safety and immunogenicity (i.e. primary immune response, immunogenicity of two different doses, antibody persistence 360 days after the first vaccination, immune response to a heterologous booster given on Day 360) of a Vero cell-derived whole virus H5N1 influenza vaccine in healthy infants, children and adolescents aged 6 months to 17 years.

Inclusion Criteria:

• 9 to 17 years of age on the day of screening (for Stratum A only)
• 3 to 8 years of age on the day of screening (for Stratum B only)
• 6 to 35 months of age on the day of screening (for Stratum C only)
• Subject who were born at full term of pregnancy (>= 37 weeks) with a birth weight >= 2 kg (for Stratum C only)
• Subjects and/or their parents/legal guardians understand the nature and procedures of the study and agree to its provisions
• Subjects´ parents/legal guardians provide written consent for participation according to national law. In case the parents/legal guardians are illiterate, the informed consent is also to be signed by an independent witness
• Written assent according to subjects´ age and capacity of understanding
• Subjects who are generally healthy, as determined by the investigator's clinical judgment through collection of medical history and performance of a physical examination
• Subjects who are physically and mentally capable of participating in the study and follow its procedures
• Subjects and/or their parents/legal guardians agree to keep a daily record of symptoms for the duration of the study
• If subjects are 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:

• History of exposure to H5N1 virus or a history of vaccination with an H5N1 influenza vaccine
• High risk of contracting H5N1 influenza infection (e.g. contact with poultry);
• Subjects who currently have or have a history of a significant neurological, cardiovascular, pulmonary (including asthma), hepatic, metabolic, rheumatic, autoimmune, hematological or renal disorder
• Inherited or acquired immunodeficiency
• Subjects who 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 corticosteroids, radiation treatment or other immunosuppressive or cytotoxic drugs.
• History of severe allergic reactions or anaphylaxis
• Rash, dermatological condition or tattoos which may interfere with injection site reaction rating
• Subjects who have received a blood transfusion or immunoglobulins within 90 days prior to study entry
• Subjects who have received any live vaccine within 4 weeks or inactivated vaccine within 2 weeks prior to vaccination in this study
• Functional or surgical asplenia
• Subjects with a known or suspected problem with alcohol or drug abuse
• Subjects who were administered an investigational drug within six weeks prior to study entry or are concurrently participating in a clinical study that includes the administration of an investigational product
• Dependent relationship with the study site personnel. Dependent relationships include close relatives (i.e., children, siblings).
• If female: subjects wo are pregnant or lactating