A study published on Wednesday in the Annals of Internal Medicine designed to test the efficacy of face mask wearing in protecting the wearer from contracting coronavirus has shown that there is no statistical significance to the wearing of face masks as protection against Covid-19 infection.
Researchers from Copenhagen University Hospital conducted the study in April and May of this year, recruiting over 6,024 volunteers with no prior coronavirus diagnosis, who were randomly assigned to either a test group or a control group. 4,862 people completed the trial, all people who spent at least three hours per day outside their homes, and who were monitored throughout.
The study was conducted at a time when mask-wearing among the Danish population was rare and the government did not mandate it. Stores, public transport, and schools remained fully operational throughout the trial, although social distancing measures were recommended (but not imposed).
Members of the test group were issued with a supply of 50 surgical masks and recommended to change them every 8 hours; around 95% of the group reported full or close to full compliance with the recommendations, which allowed for an effective comparison with the control group.
After one month, during which trial participants were monitored every week with PCR tests for development of coronavirus antibodies (i.e. the trial authors did not rely on self-reporting of Covid-19 symptoms), 1.8% of the mask-wearing group were found to have developed infection, as compared to 2.1% of the non-mask-wearing group.
The trial’s authors concluded that the effect of mask-wearing was “not statistically significant.”