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Disclosures: The authors reports no relevant financial disclosures.
February 05, 2021
2 min read

Mask mandates reduce COVID-19 hospitalizations, study suggests

Disclosures: The authors reports no relevant financial disclosures.
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COVID-19-associated hospitalizations declined by up to 5.5 percentage points at 10 hospitals located in states with mask mandates, according to data published in MMWR.

CDC economist Heesoo Joo, PhD, and colleagues assessed cumulative COVID-19-associated hospitalization rates during a 33-week span from March 1 through Oct. 17 in 99 counties from 14 states. Ten of the hospitals were in states that had issued statewide mask use.


The authors reported that weekly hospitalization rates declined by 2.9 percentage points (95% CI, 0.3-5.5) among adults aged 40 to 64 years, following mask mandates for 2 weeks.

Following mask mandates for at least 3 weeks, rates declined 5.5 percentage points in those aged 18 to 39 years (95% CI, 0.6-10.4) and in those aged 40 to 64 years (95% CI, 0.8-10.2).

“Statewide mask mandates might be associated with reductions in SARS-CoV-2 transmission and might contribute to reductions in COVID-19 hospitalization growth rates, compared with growth rates during less than 4 weeks before implementation of the mandate and the implementation week,” the authors wrote.

In a separate study, Lisa C. Barrios, DrPH, chief of the CDC’s Research Application and Evaluation Branch in the Division of Adolescent and School Health, and colleagues evaluated mask use among students at six universities — five public schools, with student populations ranging from 29,000 to 52,000, and one private school with a population of 2,300.

The authors reported that they obtained data through direct observation of individuals wearing masks on campus and at nearby off-campus locations. Each university selected 10 observation locations where mask use was mandated. A CDC staff member trained 10 student observers per university, and observers were on campuses for up to 8 weeks.

Among 17,200 individuals observed, 85.5% wore masks, among whom 89.7% wore their mask correctly (overall, 76.7%). Indoors, 91.7% wore their masks correctly. The authors said that indoor mask use was high at all six universities.

“Compliance with CDC’s recommended COVID-19 mitigation strategy of mask wearing exceeded 80% at six U.S. universities,” the authors wrote. “Mask use is likely to remain a critical COVID-19 mitigation strategy, and CDC has made the training materials used in this study available for universities that would like to monitor mask use on their campuses.”


Barrios LC, et al. MMWR Morb Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7006e1.

Joo H, et al. MMWR Morb Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7006e2.