Description and evaluation of the 2009-2010 Pennsylvania Influenza Sentinel School Monitoring System.

OBJECTIVES: We described and evaluated the 2009-2010 Pennsylvania Influenza Sentinel School Monitoring System, a voluntary sentinel network of schools that report data on school absenteeism and visits to the school nurse for influenza-like illness (ILI).
METHODS: Participating schools provided daily absenteeism and ILI data on a weekly basis through an online survey. We used participation and weekly response rates to determine acceptability, timeliness, and simplicity. We assessed representativeness by comparing participating schools with nonparticipating schools. We compared monitoring system data with statewide reports of laboratory-confirmed influenza.
RESULTS: Of the 3244 Pennsylvania public schools, 367 (11%) enrolled in the system. On average, 79% of enrolled schools completed the survey each week. Although the peak week of elevated absenteeism coincided with the peak of statewide laboratory-confirmed influenza cases, the correlation between absenteeism and state data was nonsignificant (correlation coefficient = 0.10; P = .56). Trends in ILI correlated significantly with state data (correlation coefficient = 0.67; P < .001).
CONCLUSIONS: The school-based sentinel system is a simple, acceptable, reliable device for tracking absenteeism and ILI in schools. Further analyses are necessary to determine the comparative value of this system and other influenza surveillance systems.