This is an open-label, up to four year community-based study. In each of the first three study years, school-aged children (4 through 18 years of age) who receive medical care at the Scott & White Clinics (SWCs), Temple-Belton area, Texas, will be asked to participate in this study. Study participants will receive LAIV or IIV according to their health status. Other children from Temple-Belton area who do not receive medical care at the SWC will be invited to participate in the study and may receive LAIV or IIV. A comparable population enrolled in the SWCs in Waco/McLennan County area and Bryan/College Station will serve as comparison groups.