Background: Social distancing is encouraged to mitigate viral spreading during outbreaks. However, the association between distancing and patient-centered outcomes in coronavirus disease 2019 (COVID-19) has not been demonstrated. In the United States, social distancing orders are implemented at the state level with variable timing of onset. Emergency declarations and school closures were 2 early statewide interventions.
Methods: To determine whether later distancing interventions were associated with higher mortality, we performed a state-level analysis in 55 146 COVID-19 nonsurvivors. We tested the association between timing of emergency declarations and school closures with 28-day mortality using multivariable negative binomial regression. Day 1 for each state was set to when they recorded ≥ 10 deaths. We performed sensitivity analyses to test model assumptions.
Results: At time of analysis, 37 of 50 states had ≥ 10 deaths and 28 follow-up days. Both later emergency declaration (adjusted mortality rate ratio [aMRR] 1.05 per day delay; 95% confidence interval [CI], 1.00-1.09; P = .040) and later school closure (aMRR 1.05; 95% CI, 1.01-1.09; P = .008) were associated with more deaths. When assessing all 50 states and setting day 1 to the day a state recorded its first death, delays in declaring an emergency (aMRR 1.05; 95% CI, 1.01-1.09; P = .020) or closing schools (aMRR 1.06; 95% CI, 1.03-1.09; P < .001) were associated with more deaths. Results were unchanged when excluding New York and New Jersey.
Conclusions: Later statewide emergency declarations and school closure were associated with higher Covid-19 mortality. Each day of delay increased mortality risk 5 to 6%.
Keywords: SARS-CoV-2; coronavirus; nonpharmaceutical interventions; pandemic; social distancing.
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