Background Containment of the COVID-19 pandemic requires evidence-based strategies to reduce transmission. Because COVID-19 can spread via respired droplets, many states have mandated mask use in public settings. Randomized control trials have not clearly demonstrated mask efficacy against respiratory viruses, and observational studies conflict on whether mask use predicts lower infection rates. We hypothesized that statewide mask mandates and mask use are associated with lower COVID-19 case growth rates in the United States.

Conclusions: Mask mandates and use are not associated with slower state-level COVID-19 spread during COVID-19 growth surges. Containment requires future research and implementation of existing efficacious strategies.