It was the first randomized controlled trial of more than 6,000 individuals to assess the effectiveness of surgical face masks against the virus that causes COVID-19.
- The first randomized controlled trial of more than 6,000 individuals to assess the effectiveness of surgical face masks against SARS-CoV-2 infection found masks did not statistically significantly reduce the incidence of infection
- Among mask wearers, 1.8% ended up testing positive for SARS-CoV-2, compared to 2.1% among controls. When they removed the people who did not adhere to proper mask use, the results remained the same — 1.8%, which suggests adherence makes no significant difference
- Among those who reported wearing their face mask “exactly as instructed,” 2% tested positive for SARS-CoV-2 compared to 2.1% of the controls
- 1.4% tested positive for antibodies at the end of the month-long study compared to 1.8% of controls
- 0.5% in the mask group and 0.6% tested positive for one or more respiratory viruses other than SARS-CoV-2
The first randomized controlled trial1Annals of Internal Medicine November 18, 2020 DOI: 10.7326/M20-68172Spectator November 19, 2020 to assess the effectiveness of surgical face masks against SARS-CoV-2 infection specifically — which journals initially refused to publish — finally saw seeing the light of day in November 2020.
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