A Study of Different Formulations of an A/H1N1 Pandemic Vaccine in Healthy Children Aged 6 Months to 9 Years

Inclusion Criteria : All subjects: * Provision of Informed Consent Form signed by the subject's parent(s)/legal representative (and by an independent witness if required by local regulations). In addition, provision of Assent Form signed by subjects aged 7 to 9 years * Subject and parent/guardian are able to attend all scheduled visits and to comply with all trial procedures Subjects aged 3 to 9 years: * Healthy children aged 3 to 9 years on the day of inclusion Subjects aged 6 to 35 months: * Healthy infants and toddlers aged 6 to 35 months on the day of inclusion * Born at full term of pregnancy (≥ 37 weeks) and with a birth weight ≥ 2.5 kg Exclusion Criteria : * Participation in another clinical trial investigating a vaccine, drug, medical device, or a medical procedure in the 4 weeks preceding the first trial vaccination * Planned participation in another clinical trial during the present trial period * Receipt of any vaccine in the 4 weeks preceding the trial vaccination * Planned receipt of any vaccine prior to the Day 42 blood sample * Receipt of blood or blood-derived products in the past 3 months which might interfere with the assessment of immune response * Known or suspected 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 (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months) * Se…