A Danish study released on Wednesday suggests face masks did not significantly protect wearers from the coronavirus compared to those without masks.
The study, published in the Annals of Internal Medicine, concluded that the “recommendation to wear surgical masks to supplement other public health measures did not reduce the SARS-CoV-2 infection rate among wearers by more than 50% in a community with modest infection rates, some degree of social distancing, and uncommon general mask use.”
“Recommendation to wear a surgical mask when outside the home among others did not reduce, at conventional levels of statistical significance, incident SARS-CoV-2 infection compared with no mask recommendation.”
The researchers added: “The findings, however, should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing SARS-CoV-2 infections, because the trial did not test the role of masks in source control of SARS-CoV-2 infection. During the study period, authorities did not recommend face mask use outside hospital settings and mask use was rare in community settings. This means that study participants’ exposure was overwhelmingly to persons not wearing masks.”
In short, the study gives little insight into whether a majority masked population would have an effect on reducing COVID-19 transmission. Therefore, the study is likely to have little effect on policymakers going forward who will be unable to draw conclusive findings on the efficacy masks have in places with mask mandates.
Three thousand and thirty participants were randomly assigned to wear masks, and 2,994 were assigned to the control group in the study, which took place in Denmark between April and May.
“Infection with SARS-CoV-2 occurred in 42 participants recommended masks (1.8%) and 53 control participants (2.1%),” the study reads. “The between-group difference was −0.3 percentage point (95% CI, −1.2 to 0.4 percentage point; P = 0.38) (odds ratio, 0.82 [CI, 0.54 to 1.23]; P = 0.33). Multiple imputation accounting for loss to follow-up yielded similar results. Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection.”
The study’s limitations are listed as: “Inconclusive results, missing data, variable adherence, patient-reported findings on home tests, no blinding, and no assessment of whether masks could decrease disease transmission from mask wearers to others.”
The study, which is the first published randomized clinical trial studying the effectiveness of masks against the coronavirus, comes weeks after several top journals refused to publish its findings, leading to some researchers involved questioning the motive of the journals.
Thomas Lars Benfield, one of the researchers on the study, said that it would not be published until a journal was “brave enough” but walked back those comments later, saying, “The quote [is] a bit out of context. The article is being reviewed by a respected journal. We have decided not to publish data until the article has been accepted.”
Studies conducted in the past looking at the effectiveness of face masks in stopping the spread of the coronavirus showed possible benefits but were observational studies, which Carl Heneghan of the Centre for Evidence-Based Medicine argued isn’t adequate.
“We consider it is unwise to infer causation based on regional geographical observations as several proponents of masks have done,” Heneghan said.
News of the study quickly spread on social media, with many mask critics arguing the study confirms their suspicions that mask wearing does not provide a noticeable difference in protection.
“Large scientific study of mask wearing in Denmark finally comes out: Mask wearing basically doesn’t do a damn thing,” radio host Buck Sexton tweeted. “‘Statistically insignificant.’ Scientists quoted in the article: ‘mask wearing is essential because we say so! SCIENCE!’”
Large scientific study of mask wearing in Denmark finally comes out:
Mask wearing basically doesn’t do a damn thing. “Statistically insignificant”
Scientists quoted in the article: “mask wearing is essential because we say so! SCIENCE!” https://t.co/Yl0kclmQtL
— Buck Sexton (@BuckSexton) November 18, 2020
“The Danish mask study is out and it’s the first step in recovering our collective memories from 100 years ago,” Rational Ground’s Justin Hart tweeted. “Namely – that masks don’t work.”
The Danish mask study is out and it’s the first step in recovering our collective memories from 100 years ago. Namely – that masks don’t work. https://t.co/9oJdAZXRTz
— Justin Hart (@justin_hart) November 18, 2020
“Danish mask study :After 1 mth …1.8% of the participants in the mask group and 2.1% of the participants in the control group had an infection,” author Peter Hitchens tweeted. “The study thus does not confirm the expected halving of the risk of infection of the wearer of the mouthpiece.”
Danish mask study :After 1 mth …1.8% of the participants in the mask group and 2.1% of the participants in the control group had an infection. The study thus does not confirm the expected halving of the risk of infection of the wearer of the mouthpiece https://t.co/GT6psR7DgA
— Peter Hitchens (@ClarkeMicah) November 18, 2020
“MASKS FAILED,” former New York Times reporter Alex Berenson tweeted. “Least surprising finding ever.”
Link to abstract: https://t.co/oF9ZRCuyNG
— Alex Berenson (@AlexBerenson) November 18, 2020
The study comes during a time when mask wearing has become a contentious political issue, with prominent Democrats, including President-elect Joe Biden, calling for states to impose mask mandates in line with Centers for Disease Control and Prevention guidance.
On the other side, prominent Republicans, including South Dakota Gov. Kristi Noem and Sen. Rand Paul, have pushed back on that plan and questioned the need for masks and the authority to impose a mandate.
Author: Andrew Mark Miller