The effect of reactive school closure on community influenza-like illness counts in the state of Michigan during the 2009 H1N1 pandemic

Clin Infect Dis. 2015 Jun 15;60(12):e90-7. doi: 10.1093/cid/civ182. Epub 2015 Apr 20.


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.

Keywords: influenza; influenza-like illness; nonpharmaceutical interventions; school closure.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Disease Outbreaks / prevention & control*
  • Disease Outbreaks / statistics & numerical data*
  • Humans
  • Influenza A Virus, H1N1 Subtype*
  • Influenza, Human / epidemiology*
  • Influenza, Human / prevention & control*
  • Michigan / epidemiology
  • Schools