The vaccine prevented influenza associated illness in approximately 87% of the 60 - 71 month old children included in the trial. Adults (ages 18-49 years) who received FluMist experienced significantly fewer episodes of severe febrile illness (SFI) when compared to those who received placebo. Severe febrile illness was defined as having at least three days of symptoms (runny nose, sore throat, cough, muscle aches, tiredness/weakness) and one day of fever. Adults who received FluMist did not experience a significant reduction in any febrile illness (AFI). Adults were characterized as having AFI if they had symptoms for at least two consecutive days, with fever on at least one day. As with any vaccine, FluMist may not protect 100% of individuals receiving the vaccine. | 
