School-Based Influenza Vaccination Clinics and Student Absenteeism during Influenza Season — Arkansas, 2012 – 2013

BACKGROUND:  Influenza is a viral respiratory illness that peaks seasonally during December – March. It is a major cause of morbidity among school-aged children. Children are widely recognized as efficient transmitters of influenza in both schools and the community. Accordingly, the Arkansas Department of Health coordinates >800 school-based influenza immunization clinics before each influenza season. We examined the relationship between the percentage of students vaccinated during school-based clinics and school absenteeism during the 2012 – 2013 influenza season in Arkansas public schools to quantify the effects of vaccination on absenteeism.

METHODS:  Data from school-based vaccination clinics were reported via a web-based system by clinic nurses. Data elements included the clinic date, location, and total number of vaccinations given. The number of students absent daily and the number of students enrolled in Arkansas public schools were obtained from the Arkansas Department of Education. Linear regression models examined the ecologic association between the percentage of students vaccinated and the average daily percentage of students absent during the time period January 7 – March 1, 2013.

RESULTS:  The final dataset included 422 public schools with documentation of absenteeism and vaccination clinic data. School absenteeism during January 7 – March 1, 2013 ranged from 0.6% to 15.4% of students absent per day. All school types were included; however, primary schools comprised 58% of the schools included in this analysis. A total of 77,239 doses of influenza vaccination were given among the 422 clinics. School enrollment averaged 481 students (range: 52 – 2,073). An unadjusted linear regression model examining the association between average daily absenteeism during influenza season and the percentage of students vaccinated predicted a 0.031% decrease in daily absenteeism for every 1% increase in students vaccinated (p<0.0001, adjusted R² = 0.0544). After adjusting for school size, the model predicted a 0.027% decrease in school absenteeism with a 1% increase in the percentage of students vaccinated (p=0.0002, adjusted R² = 0.0834).

CONCLUSIONS:  Extrapolation of the adjusted linear regression model indicates that a 10% increase in vaccination coverage among Arkansas public school students could result in over 76,800 preventable student absentee days during a 12-week influenza season. Influenza vaccination is an effective tool to reduce school absenteeism, which may facilitate scholastic achievement and minimize school district costs relating to student and staff absenteeism. School-based clinics are a proven and feasible way to target influenza vaccinations to school-aged children.