Study: Mask Mandates Didn't Help Slow Spread of COVID-19

Mask use was associated with slowed COVID-19 spread, but only during periods of low case growth. A new study suggests state mask mandates didn't help slow COVID-19 transmission. The pre-publication study found "qualitatively comparable courses of viral spread" among states with early, late, and no mask mandates.

Mask use—defined as "the percentage of people who always wear masks in public settings"—was associated with slower spread during low-transmission periods. But it was not associated with slower spread during high-transmission periods.

Going into the study, lead author Damian D. Guerra, an assistant professor of biology at the University of Louisville, and...