The purpose of this study is to compare the safety and effectiveness (immune response) to one or two doses of adjuvanted H1N12009 influenza vaccine in young children. An adjuvant is an additive that can boost the immune response. The study will enroll 300 children (ages 6-35 months). Participants will receive 2 doses of adjuvanted H1N12009 vaccine 3 weeks apart. Study procedures include: medical history, blood samples and completing a memory aid. Participants will be involved in study related procedures for approximately 6 weeks.

The goal of this study is to determine if one or two doses of the H1N12009 influenza vaccine are needed in young children, a population group at high risk of influenza infection and subsequent hospitalization.

The objectives of this study are two-fold:

1. To compare the safety and immunogenicity of 1 and 2 doses of adjuvanted H1N12009 influenza vaccine in children 6-35 months of age.
2. To conduct the trial soon after the vaccines become available and share the observations with health officials and the public as soon as possible.

Inclusion Criteria:

• Written informed consent provided for the subject by a parent or legal guardian
• Children age 6-35 months

Exclusion Criteria:

• Allergies to eggs, thimerosal, gentamicin sulphate or latex
• Life-threatening reaction to previous Flu vaccine
• Bleeding disorder
• Pregnancy
• Receipt of blood or blood products in past 3 months
• Chronic illness that could interfere with trial participation
• Compromised immune system
• Previous lab-confirmed H1N12009 infection
• Receipt of H1N12009 vaccine
• Receipt of Seasonal Influenza vaccine since March 2009