Community Use Of Face Masks And COVID-19: Evidence From A Natural Experiment Of State Mandates In The US

Health Aff (Millwood). 2020 Aug;39(8):1419-1425. doi: 10.1377/hlthaff.2020.00818. Epub 2020 Jun 16.


State policies mandating public or community use of face masks or covers in mitigating the spread of coronavirus disease 2019 (COVID-19) are hotly contested. This study provides evidence from a natural experiment on the effects of state government mandates for face mask use in public issued by fifteen states plus Washington, D.C., between April 8 and May 15, 2020. The research design is an event study examining changes in the daily county-level COVID-19 growth rates between March 31 and May 22, 2020. Mandating face mask use in public is associated with a decline in the daily COVID-19 growth rate by 0.9, 1.1, 1.4, 1.7, and 2.0 percentage points in 1-5, 6-10, 11-15, 16-20, and 21 or more days after state face mask orders were signed, respectively. Estimates suggest that as a result of the implementation of these mandates, more than 200,000 COVID-19 cases were averted by May 22, 2020. The findings suggest that requiring face mask use in public could help in mitigating the spread of COVID-19.

Keywords: Covid-19; Evidence based decision making; Face masks; Health professionals; N95; Pandemics; Populations; Publish health; Researchers; State health policies; State mandates; coronavirus.

Publication types

  • Review

MeSH terms

  • COVID-19
  • Communicable Disease Control / organization & administration*
  • Coronavirus Infections / epidemiology
  • Coronavirus Infections / prevention & control*
  • Female
  • Humans
  • Male
  • Mandatory Programs / legislation & jurisprudence*
  • Masks / statistics & numerical data*
  • Needs Assessment
  • Pandemics / prevention & control*
  • Pandemics / statistics & numerical data
  • Pneumonia, Viral / epidemiology
  • Pneumonia, Viral / prevention & control*
  • Public Health / legislation & jurisprudence*
  • Public Health / methods
  • United States