This study provided comparisons of confirmed cases between face-cover-required states and partially or not-required states from a time-series analysis on effects of face mask use in public based on eight different states between March 1 and June 15, 2020. In comparing face-cover-required states and partially or not-required states, it was very encouraging that the slope of the daily case trends turned negative after face-cover requirements in statewide face-cover-required states, including New York, New Jersey, Pennsylvania, and Connecticut. However, the patterns of the daily case have been showing positive trends continuously in partially or not-required states, including California, Texas, Florida, and Virginia. Based on our prediction model, if nationwide face-cover requirements with social distancing were enacted on March 16, the estimated number of deaths would be about 15,600, which is 94,300 less than the actual number of deaths by June 15, 2020. We recommend that all states and the federal government require face coverings in order to reduce the risk of infectious diseases.
Keywords: COVID‐19; data analytics; face‐cover requirement.
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