Rapid Evaluation of Pandemic H1N1 Influenza Vaccine in Adults Receiving Seasonal Influenza Vaccine

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.