Mask...

Background: COVID-19 pandemic mitigation requires evidence-based strategies. Because can spread via respired droplets, most US states mandated mask use in public settings. Randomized control trials have not clearly demonstrated efficacy against respiratory viruses, and observational studies conflict on whether predicts lower infection rates. We hypothesized that statewide mandates were associated with case growth rates the United States. Methods: calculated total for continental States data from Centers Disease Control Prevention Institute Health Metrics Evaluation. estimated post-mask mandate non-mandate using median issuance dates of neighboring mandates. Results: Earlier cases or maximum weakly minimum Mask predicted but Growth comparable between first last quintiles during Fall-Winter wave. These observations persisted both natural logarithmic fold models when adjusting differences state population density. Conclusions: did observe association reduced states. further research existing efficacious strategies, notably vaccination.