Lower COVID-19 rates seen in US states with higher adherence to mask wearing

A new state-by-state analysis shows a statistical association between high adherence to mask wearing and reduced rates of COVID-19 in the U.S. Charlie Fischer and colleagues at the Boston University School of Public Health in Massachusetts present these findings in the open-access journal PLOS ONE on April 14.

During the COVID-19 pandemic, different states have enacted different policies on mask wearing, with some states having no mask requirements and others requiring masks in all public spaces. Understanding the link between mask wearing and COVID-19 rates could help inform policies to mitigate stress on healthcare systems, economic instability, and death.

To help clarify the effects of mask wearing, Fischer and colleagues examined publicly available data on mask-wearing policies, people’s self-reported habits on mask wearing in public, and COVID-19 rates for all 50 U.S. states and Washington, D.C. They accounted for a one-month delay between mask wearing and its subsequent potential impact on COVID-19 rates from May through October 2020. For this analysis, they considered rates of more than 200 cases per 100,000 residents to be high.

The analysis showed that, out of 15 states that did not require people to wear masks in public, 14 had high COVID-19 rates. Meanwhile, eight states had self-reported adherence rates of 75 percent of greater, and none of these states had a high COVID-19 rate. States with the lowest adherence rates had the greatest likelihood of high COVID-19 rates in the subsequent month.

The eight states with at least 75-percent adherence to mask wearing had a mean COVID-19 rate of 109.26 per 100,000 residents in the subsequent month, while the mean COVID-19 rate was 239.99 for states with less than 75 percent adherence.

These findings provide new evidence in support of mask-wearing as a major factor that contributes to reduced COVID-19 rates. They suggest that policies and public health efforts to reduce the spread of COVID-19 should include a focus on improved mask adherence throughout the U.S.

 Public Library of Science