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Emergency Medical Minute


Nov 30, 2020

Contributor: Peter Bakes, MD

Educational Pearls:

  • Recent study looked at if mask wearing protects the mask wearer from infection
  • This group found 1.8% of mask wearers got COVID while 2.1% of non-mask wearers became infected, which was not statistically significant
  • This was not statistically significant and has been used to justify not wearing masks by some groups
  • While the numbers look small, it's close to a 20% reduction in infections for the mask wearers
  • The results reported had concerns for being underpowered, meaning the studies population may not be big enough to draw definitive conclusions
  • Many limitations of study including how wearing a mask may protect others
  • Unfortunately, studies like these can lead to misinterpretation and distortion


Bundgaard H, Bundgaard JS, Raaschou-Pedersen DET, von Buchwald C, Todsen T, Norsk JB, Pries-Heje MM, Vissing CR, Nielsen PB, Winsløw UC, Fogh K, Hasselbalch R, Kristensen JH, Ringgaard A, Porsborg Andersen M, Goecke NB, Trebbien R, Skovgaard K, Benfield T, Ullum H, Torp-Pedersen C, Iversen K. Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers : A Randomized Controlled Trial. Ann Intern Med. 2020 Nov 18. doi: 10.7326/M20-6817. Epub ahead of print. PMID: 33205991.

Summarized by Jackson Roos, MS4 | Edited by Erik Verzemnieks, MD


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