Early evidence for effectiveness of statewide school closure for mitigation of influenza

Abstract

Background: School closures were mandated in response to COVID-19 as a nonpharmaceutical intervention. Infl uenza A was widespread in Wisconsin at the time of mandate, March 18, 2020, allowing its evaluation for infl uenza interruption.Methods: Daily percent positivity of infl uenza A among primary care patients who received a rapid infl uenza diagnostic test was evaluated throughout two infl uenza seasons while schools were open and closed.Results: Median deviation from baseline of percent positivity was signifi cantly lower when schools were closed than when open (-2.25% vs 1.08%; H=7.84; P=0.005). Median deviation in percent positivity for the eight days following statewide school closure was -20.0.Discussion: Unprecedented closures of all Wisconsin schools was associated with a rapid decline in infl uenza A. Additional evaluations within other jurisdictions are warranted.