The hypothesis is that universal vaccination of healthy school-aged children is an alternative and effective strategy for the control of epidemic influenza, and will serve as a model for the control of pandemic influenza and biodefense. The specific aims of the study are: to control the spread of influenza to susceptible adults 35 years of age or older by vaccination of school-aged children 4-18 years of age; to control the spread of influenza to susceptible children and young adults less than 35 years of age by vaccination of school-aged children 4-18 years of age; to develop a school-based vaccination program for rapid and timely delivery of LAIV and IIV to children 4-18 years of age; to demonstrate in school-aged children the direct and total effectiveness of influenza vaccines to reduce the rates of medically attended acute respiratory illness (MAARI) in LAIV and IIV recipients during influenza epidemics; and to capture safety information on LAIV post-licensure.