Table 1.
Setting | Exposure of interest | Effect |
---|---|---|
USS Theodore Roosevelt aircraft carrier | face coverings during an outbreak | service members who wore face coverings had lower infection rate than those who did not (55.8% versus 80.8%) |
Hair salons in Missouri | two masked hair stylists infected with COVID-19 exposed 139 clients, all masked | none of the 139 clients developed symptoms with 67 testing negative for SARS-CoV-2 |
Boston health care settings | institution of universal surgical masking with provision in hospitals | significantly lower rate of SARS-CoV-2 positivity among health care workers after masking |
Arizona during summer surge | mask mandates, limiting large crowds, social distancing | transmission rates were up by 151% prior to these measures and then stabilized and decreased by 75% with continued application |
Kansas counties during summer surge | state mask mandate with option for counties to opt-out in Kansas | COVID-19 incidence decreased in 24 counties with mask mandates after July 3, but continued to increase in 81 counties without mask mandates4 |
Tennessee counties | mask requirements | areas with mask requirements had a slower growth rate in hospitalizations for COVID-19 (without controlling for cases) than those without mask requirements6 |
States in the U.S. | mask mandates in 15 states and Washington, DC over summer | reduction in COVID-19 transmission rates in states mandating face mask use in public compared to those without mandates |
Germany | regional mandates for mandatory mask wearing in public transport and shops | face masks reduced the number of new COVID-19 infections 45% (between 15% and 75%) over a period of 20 days after the mandates5 |
∗Unless indicated, all references are found in the CDC Scientific Brief2