The main purpose of this study is to learn if influenza vaccines (live attenuated and inactivated influenza vaccines), when given to school-aged children 4 to 18 years of age, can stop or lessen the influenza (flu) outbreak in the community. Another purpose is to show that vaccination of these children will significantly reduce breathing problems (in the vaccinated children and unvaccinated people they come in contact with in the community) that require a visit to the doctor for treatment. Another purpose is to continue to collect safety and flu protection information on live attenuated influenza vaccine (LAIV or FluMist) given to children. The study investigators believe that vaccination of healthy school-aged children is an effective plan for preventing many people in the community from catching the flu. Children will take part in the study for 5 to 10 months.