The purpose of this study is to assess the safety and effectiveness (immune response) to a licensed H1N12009 influenza vaccine in adults when given at the same time or prior to the seasonal influenza vaccine. The study will enroll 300 adults (ages 20-59 years). Participants will be randomized into 2 groups. One group will receive one dose of a licensed H1N1 vaccine and one dose of the seasonal influenza vaccine at the same time; the second group will receive the seasonal influenza vaccine 3 weeks after receiving the licensed H1N12009 influenza vaccine. Study procedures include: medical history, blood samples and completing a memory aid. Participants will be involved in study related procedures for approximately 3-6 weeks depending upon the group assignment.

The objectives of this study are two-fold:

1. To evaluate the safety and immunogenicity of H1N12009 influenza vaccine in a convenience sample of adults, soon after the pandemic vaccine becomes available so as to inform the subsequent use of vaccine in public programs.
2. To evaluate the compatibility of co-administered H1N12009 pandemic vaccine and seasonal TIV vaccine in the same group of subjects, as the option of co-administration would be useful for public programs.

Inclusion Criteria:

• Written informed consent
• Adults 20-59 years of age

Exclusion Criteria:

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