A pilot study of the effectiveness of a school-based influenza vaccination program.

Objective: The objective of this study was to evaluate the feasibility of a school-based influenza immunization program.

Methods: Pupils and their families from 3 demographically similar elementary schools participated in this pilot, unblinded, controlled intervention study. Live attenuated influenza vaccine (FluMist) was made available to all eligible pupils in 1 target school during regular school hours. Two schools where vaccine was not offered served as control schools. All families from the 3 study schools were sent an anonymous questionnaire requesting 7-day recall data on fever or respiratory illness (FRI)-related medical visits, medications purchased, and days of school or paid work lost during the peak influenza week. Changes in weekly pupil absenteeism were also examined.

Results: One hundred eighty-five (40%) of the target school pupils received vaccine, of whom >50% were vaccinated < or =3 weeks before the influenza outbreak period. Questionnaires were returned by 43% to 51% of households. Significant (45-70%) relative reductions in FRI-related outcomes, including doctor visits by adults or children, prescription or other medicines purchased, and family schooldays or workdays missed, were observed for target school households, compared with control school households. The increases in absenteeism rates during the influenza outbreak period, compared with baseline rates earlier in the fall, were not significantly different between target and control schools. Within the target school, however, the increase in absenteeism rates was significantly smaller for the FluMist-vaccinated pupils, compared with the non-FluMist-vaccinated pupils.

Conclusions: This school-based influenza immunization program was associated with significant reductions in FRI-related outcomes in households of pupils attending an intervention school. These results might have underestimated the potential impact of FluMist, because the majority of children received intraepidemic vaccination.