摘要：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. The emergence of pandemic influenza A (pH1N1) in spring 2009 had a disproportionate impact on school-aged children. 1 , 2 More than half of the reported cases of pH1N1 in the United States were among children younger than 18 years. 3 Although preexisting immunity in older age groups may have contributed to this pattern of disease, 4 schools may also have played an important role in amplifying transmission of the virus. 5 School-aged children are known to play an important role in the epidemiology of influenza. 6 – 8 A typical ill student infects an estimated 2.4 (95% confidence interval [CI] = 1.8, 3.2) other children within a school. 9 Children may also serve as the means of introduction of influenza infection into households during seasonal influenza outbreaks. 10 – 13 Attack rates in adults who reside with school-aged children may be 2 to 3 times higher than are attack rates in similar adults who do not reside with school-aged children. 8 Because pH1N1 heavily affected school-aged children, and because children play an important role in the transmission of flu, it is important to closely follow the occurrence of influenza and related indicators in this population. In fact, influenza activity in schools may be an important early indicator of activity in the general population, 14 and schools are of particular importance for controlling influenza. 7 , 15 , 16 Although it is not possible to directly monitor influenza in all schools, using sentinel school absenteeism data as a proxy for data on influenza prevalence in the community may be warranted. 14 , 17 , 18 Recognizing the atypical epidemiology of pH1N1 and the importance of early influenza detection, local, state, and federal public health agencies made schools an early focus of monitoring, prevention, and control activities. In May 2009, the Pennsylvania Department of Health (PADOH) recommended that all schools monitor and report to public health authorities excess absenteeism that may be related to influenza. In a follow-up to this recommendation, for the 2009–2010 school year the PADOH established a voluntary sentinel network of elementary, middle, and high schools around the state to report weekly counts of student absenteeism and visits to the school nurse for influenza-like illness (ILI). After 1 school year of collecting surveillance data from schools, we evaluated this monitoring system.
