Effectiveness of adding mask recommendations to other COVID-19 public health measures

Editor's Note

This randomized, controlled trial by Danish researchers finds that wearing surgical masks to supplement other public health measures did not significantly reduce the COVID-19 infection rate, compared with no mask.

Of 6,024 trial participants, 3,030 were randomly assigned to wear high-quality surgical face masks with a filtration rate of 98%, and 2,994 were assigned not to wear face masks. Participants spent a median of 4.5 hours per day outside the home.

A total of 42 (1.8%) participants in the mask group tested positive for COVID-19, and 53 (2.1%) tested positive in the non-mask control group.

The results suggest that the recommendation to wear a surgical mask when outside the home did not reduce, at conventional levels of statistical significance, the incidence of COVID-19 in mask wearers in a setting where social distancing and other public health measures were in effect.