Selective: Danish Face Mask Study

Tracy Davenport

Health

2nd December 2020

The study only measured whether masks benefitted the mask wearer (Getty Images).

The Claim

A Danish study found that facemasks don’t work.

News posted on

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Emerging story

Danish researchers investigated the effect of using a face mask as a supplement to other measures against infection of COVID-19. After seeing the study results, social media users claimed that facemasks do not work to reduce virus spreading.

Misbar’s Analysis

Misbar has discovered that Danish researchers investigated whether mask-wearing reduced transmission of COVID-19. The findings were published in the Annals of Internal Medicine. The research observed 3030 adults who wore masks and 2994 adults who did not wear masks to determine the COVID-19 infection rate after one month. The adults were outside of their homes at least three hours per day.

It was determined that 42 mask wearers (1.8%) versus 53 non-mask wearers (2.1%) were infected with COVID-19. The difference between the two groups was not statistically significant, meaning, there was really no difference that was not attributed to chance.

However, the authors of the study conclude that the findings should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing COVID-19 infections because the trial did not test whether masks could decrease transmission from mask wearers to others.

Because the Danish study only measured whether masks benefitted the mask wearer and not whether masks helped with disease transmission, the claims on social media are selective.