Prepandemic influenza vaccine (H5N1)(Baxter International, Inc.)

This study is a prospective surveillance of the immune response to seasonal vaccination in healthy children. The study will enroll a total of approximately 220 subjects. 140 children will be vaccinated with inactivated influenza vaccine (IIV) and will be divided into 4 age cohorts: 20 children between 6-12 months of age, 60 children greater than 12 months of age and born after 2009, 30 children with a birth date between 2006 and 2009, and 30 children with a birth date between 2003 and 2006. 80 children presenting with natural influenza infection prior to receipt of influenza vaccination also will be divided into 4 age cohorts: 20 children between 3-12 months of age, 20 children greater than 12 months of age with a birth date after 2009, 20 children with a birth date between 2006 and 2009, and 20 children with a birth date between 2003 and 2006. Influenza vaccines will be administered using age-appropriate guidelines in all years of the study: Fluzone 0.25 mL administered intramuscularly to children between 6 and 35 months of age and 0.5 mL to children 36 months of age and older. Subjects will be seen at one domestic site and their participation duration is 2 influenza seasons plus 1 optional season. The primary hypothesis being tested in this study is that there will be differences in the specificity, magnitude and functionality of CD4 T cell and B cell reactivity in a cohort of children depending on early childhood exposures. The primary objective of this study is to evaluate the relationship between influenza virus exposure, infection and vaccine history, and CD4 T cell reactivity in a cohort of children with well documented influenza exposures.

The study will be designed as a prospective surveillance of the immune response to seasonal influenza vaccination in 240 healthy children and adults ages 9 and over. Study duration will be 5 years, with a participant duration of 6 months. Subjects will receive a quadrivalent inactivated influenza vaccine, at a dose of not less than 15 ug of hemagglutinin (HA), by intramuscular injection in open label fashion on day 0. Blood draws will occur at baseline, day 7, 28 and 90. The primary objective of this study is to evaluate the relationship between first influenza A virus exposure (inferred by age), vaccine history, and baseline serum antibody response to seasonal influenza vaccine in healthy adults and children.