Association between COVID-19 outcomes and mask mandates, adherence, and attitudes
Fig 1
Effect of state-level mask mandates on COVID-19 outcomes.
Shaded area represents 95% confidence interval, with standard errors clustered at the state level. Red vertical line represents the start of the mask mandate, and the red horizontal line represents the line of zero treatment effect. We observe the treatment effect to start near zero when mask mandates are introduced (red vertical line) and to gradually increase (i.e. the treatment effect becomes more negative) reaching, 40 days after the introduction of mask mandates, -0.49 standard deviations (95% confidence interval is [-0.61,-0.37], adjusted R2 is 0.632 and p < 0.001) for new cases (a), -2.38 percentage points ([-2.99,-1.78], adjusted R2 is 0.698 and p < 0.001) for the proportion of daily hospitalization admissions (b) due to COVID-19, and 0.52 standard deviations (95% confidence interval is [-0.69,-0.35], adjusted R2 is 0.537 and p < 0.001) for deaths (c). These effects are large, corresponding to 14% of the highest recorded number of cases, 13% of deaths, and 7% of admission proportion.