At the start of the COVID-19 outbreak, each additional day that states delayed declaring an emergency was associated with a 5% increase in mortality, a study has found.
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The imposition of physical distancing measures by state governments during the COVID-19 pandemic has been politically controversial in the United States.
Critics have questioned the necessity and effectiveness of such measures, particularly in light of the considerable economic costs.
In the absence of direct evidence early in the outbreak, as the number of local cases mounted, states based their decisions to close schools and declare an emergency on modeling studies and evidence from past epidemics.
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A 2007 analysis of the influenza pandemic of 1918–1919, for example, found that earlier closure of schools and bans on public gatherings by U.S. city authorities was associated with lower subsequent mortality in those cities.
Researchers in Philadelphia, PA, have now published one of the first studies specifically assessing the effect of physical distancing on COVID-19 death rates.
They used the unambiguous dates when states declared emergencies and closed schools as proxies for when each began to implement significant physical distancing measures.
“Before this study, we assumed social distancing worked based on modeling and studies of prior pandemics, but we didn’t have substantial quantitative data to show its effectiveness for COVID-19,” says lead author Nadir Yehya, assistant professor in the Department of Anesthesiology and Critical Care Medicine at the Children’s Hospital of Philadelphia and the University of Pennsylvania.
“Our analyses demonstrate that states that issued emergency declarations earlier helped curb the spread of the disease,” he says. “These results confirm how important it i