title: The effect of reactive school closure on community influenza-like illness counts in the state of Michigan during the 2009 H1N1 pandemic.
abstract: BACKGROUND
  In sum, 559 Michigan schools were closed as a nonpharmaceutical intervention during the influenza A 2009 (H1N1) pandemic.
  
  
  METHODS
  By linking the proportion of schools closed within a district to state influenza-like illness (ILI) surveillance data, we measured its effect on community levels of ILI. This analysis was centered by the peak week of ILI for each school district, and a negative binomial model compared three levels of school closure: 0%, 1%-50%, and 51%-100% of schools closed from three weeks leading up to ILI peak to four weeks following ILI peak rate.
  
  
  RESULTS
  We observed that school closures were reactive, and there was no statistically significant difference between ILI rates over the study period. There was an elevated rate ratio for ILI at 51%-100% closure, and a reduction in the rate ratio at the 1%-50% compared to the 0% closure level.
  
  
  CONCLUSIONS
  These findings suggest that district level reactive school closures were ineffective.
authors.affiliation: Epidemiology Department, University of Michigan School of Public Health.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Davis
authors.affiliation: Center for the History of Medicine, University of Michigan Medical School, Ann Arbor.
authors.forename: Howard
authors.initials: H
authors.lastname: Markel
authors.affiliation: Center for the History of Medicine, University of Michigan Medical School, Ann Arbor.
authors.forename: Alex
authors.initials: A
authors.lastname: Navarro
authors.affiliation: Epidemiology Department, University of Michigan School of Public Health.
authors.forename: Eden
authors.initials: E
authors.lastname: Wells
authors.affiliation: Epidemiology Department, University of Michigan School of Public Health.
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Monto
authors.affiliation: Epidemiology Department, University of North Carolina Gillings School of Global Public Health, Chapel Hill.
authors.forename: Allison E
authors.initials: AE
authors.lastname: Aiello
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control* / Q000706:statistics & numerical data*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control*; D008824:Michigan / Q000453:epidemiology; D012574:Schools
keywords: influenza; influenza-like illness; nonpharmaceutical interventions; school closure