State requirements to wear face masks in public may have prevented hundreds of thousands of additional COVID-19 cases in the U.S., according to a study published in Health Affairs.
Researchers found the daily COVID-19 growth rate significantly declined after Washington, D.C., and 15 states issued mask mandates between April 8 and May 15. States that only recommended the use of masks in public did not see comparable declines.
Researchers estimate the mask mandates may have prevented an additional 230,000 to 450,000 COVID-19 cases by May 22.
The findings are based on statistical modeling using daily county-level data of confirmed COVID-19 cases between March 25 and May 21.
Requiring Americans to wear face masks in public may help reduce the virus's spread, especially if there is a major resurgence this fall, researchers concluded.