Inclusion Criteria :

All subjects:

• Able to attend all scheduled visits and to comply with all trial procedures.

Children/Adolescents aged >= 2 years to < 18 years:

• Aged >= 2 years to < 18 years on the day of inclusion.
• Informed Consent Form signed by one parent or another legal representative and by an independent witness if the parent/legal representative is illiterate.
• For a female, inability to bear a child or negative urine pregnancy test (as applicable).
• For a female of child-bearing potential, use of an effective method of contraception or abstinence for at least 4 weeks prior to the first vaccination and at least 4 weeks after the last vaccination (as applicable).

Infants/toddlers aged >= 6 months to < 2 years:

• Aged >= 6 months to < 2 years on the day of inclusion.
• Born at full term of pregnancy (>= 37 weeks) with a birth weight >= 2 kg.
• Informed Consent Form signed by one parent/legally acceptable representative and an independent witness if the parent/legally acceptable representative is illiterate.
• Subject who completed vaccination according to the national immunization schedule.

Exclusion Criteria :

All subjects:

• Participation in another clinical trial in the 4 weeks preceding the first trial vaccination.
• Planned participation in another clinical trial during the present trial period.
• Congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroid therapy.
• Systemic hypersensitivity to any of the vaccine components or history of life threatening reaction to the trial vaccine or a vaccine containing the same substances (egg proteins, chick proteins, thimerosal, aluminum, neomycin, formaldehyde, and octoxinol 9).
• Chronic illness at a stage that could interfere with trial conduct or completion.
• Blood or blood-derived products received in the past 3 months.
• Any vaccination in the 4 weeks preceding the first trial vaccination.
• Vaccination planned in the 4 weeks following any trial vaccination.
• History of the H5N1 infection (confirmed either clinically, serologically or virologically).
• Known HIV, Hepatitis B (HBsAg) or Hepatitis C seropositivity.
• Previous vaccination with an avian flu vaccine.
• Subject at high risk of the H5N1 infection during the trial.
• Thrombocytopenia or bleeding disorder contraindicating IM vaccination.
• Febrile illness (rectal equivalent temperature >= 38.0°C) on the day of inclusion.

Children/Adolescents aged >= 2 years to < 18 years:

• Breast-feeding mothers.
• Current alcohol abuse or drug addiction that may interfere with the subject's ability to comply with trial procedures (if applicable, depending on the subject's age).

Infants/toddlers aged >= 6 months to < 2 years:

• History of seizures.