To measure the effectiveness of influenza vaccination in school children by comparing, between target(i.e., children are offered FluMist) and control (i.e., children are not offered FluMist) school families.

Inclusion Criteria:

• Healthy children enrolled in the target schools.
• Written informed consent obtained from the child's parent(s) if they agree to participate.

Exclusion Criteria:

• History of severe hypersensitivity (anaphylactic response) to egg products or previous FluMist
• FluMist is licensed exclusively for use in healthy individuals age 5-49 years. Therefore children for whom annual receipt of inactivated influenza vaccine for specific medical condition(s) is recommended will not be eligible. These conditions include:
• Asthma, other chronic pulmonary diseases, kidney disease, metabolic disease, heart disease, or hemoglobinopathy
• Immunosuppression of child
• Severe immunosuppression of a household member
• Pregnancy
• Past history of Guillian-Barre Syndrome
• Aspirin therapy within 1 month prior to FluMist or the anticipated use of aspirin containing products for one month after FluMist administration
• Administration of any inactivated vaccine within 2 weeks or any live vaccine within 4 weeks prior to receipt of FluMist
• Received anti-influenza medication in the past 48 hours
• Fever in the past 72 hours
• Moderate to severe nasal congestion (inability to breathe through the nose) or acute phase URI symptoms until the congestion has improved