A Study of Different Formulations of an A/H1N1 Pandemic Vaccine in Healthy Adults and the Elderly

Inclusion Criteria : * Healthy adults aged 18 years or older on the day of inclusion * Informed consent has been signed and dated * Able to attend all scheduled visits and comply with all trial procedures * For a woman of child-bearing potential, use of an effective method of contraception or abstinence from at least 4 weeks prior to the first vaccination, until at least 4 weeks after last vaccination. Exclusion Criteria : * Known pregnancy or positive urine pregnancy test * Currently breastfeeding a child * 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) * Self-reported seropositivity for Human Immunodeficiency Virus (HIV), Hepatitis B antigen, or Hepatitis C * Known systemic hypersensitivity to any of the vaccine compon…