1; Florence C. Lee, MPH1; Gregory Sunshine, JD1; Russell McCord, JD1; Mara Howard-Williams, JD2; Lyudmyla Kompaniyets, PhD1; Christopher Dunphy, PhD1; Maxim Gakh, JD3; Regen Weber1; Erin Sauber-Schatz, PhD1; John D.
Omura, MD1; Greta M. Massetti, PhD1; CDC COVID-19 Response Team, Mitigation Policy Analysis Unit; CDC Public Health Law Program (View author affiliations)Universal masking and avoiding nonessential indoor spaces are recommended to mitigate the spread of COVID-19.Mandating masks was associated with a decrease in daily COVID-19 case and death growth rates within 20 days of implementation.