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Despite what you may have seen on social media, a new study from researchers in Denmark did not find that masks don’t work in slowing the spread of COVID-19. Anyone making such a claim didn’t closely review the study’s findings, or is willfully misrepresenting them. Either way, this is spreading dangerous misinformation.
The immediacy with which certain pundits, activists and even members of Congress inaccurately portrayed the Danish study is telling. It underscores a desire to quickly feed a narrative against mask wearing, facts be damned.
The large randomized study of nearly 5,000 Danish participants took place in April and May, and was published Wednesday in the Annals of Internal Medicine. Participants were divided into two groups: one that received masks and a recommendation to wear them, and another control group that did not.
The researchers expected that the masked group would see a more than 50 percent reduction in the rate of COVID-19 infection. That didn’t happen. The masked group did see a slightly smaller rate of infection of 1.8 percent compared to 2.1 percent of the control group, but that difference is not considered statistically significant.
Some people have tried to seize on those results as some sort of proof that masks aren’t effective in the battle against COVID-19. But to make this false argument, people have to ignore the study’s stated limitations, especially that there was no assessment about whether masks can diminish the risk of transmission from infected people to others around them (referred to as “source control”).
The fact is that the Danish study’s findings do not show masks to be ineffective in limiting the spread of SARS-CoV-2, the virus that causes COVID-19. Research abstracts can sometimes seem, well, abstract to us non-scientists. But on this point, the study’s authors were very clear.
“These findings do offer evidence about the degree of protection mask wearers can anticipate in a setting where others are not wearing masks and where other public health measures, including social distancing, are in effect,” the authors said. “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.”
So, anyone trying to use this study to make a blanket statement saying masks don’t work is contorting the findings in a way the authors expressly said not to. Such claims, issued almost immediately after the study was published, are blatant and irresponsible attempts to attach some shred of scientific legitimacy to mask-wearing resistance — to take selfishness and try to launder it as science.
Contrary to what some have claimed, the Danish researchers did not find that masks don’t work. They found that masks didn’t protect the wearer nearly as much as was expected. Those are not remotely the same things.
Public health officials have been stressing since April to wear a mask to help protect others. This study doesn’t change that one bit. And despite raising questions, it doesn’t necessarily undermine the U.S. Centers for Disease and Control Prevention recent scientific brief concluding that masks have a prevention benefit for both the wearer and people around them. At the time that the Danish study was conducted, mask wearing was not common there. That could have limited the protection provided by wearing a mask.
“The relationship between source control and personal protection is likely complementary and possibly synergistic, so that individual benefit increases with increasing community mask use,” the CDC concluded earlier this month.
Above all, the Danish study reiterates an important point: don’t treat your mask as armor. Masks don’t make you impervious to the virus. Wearing a mask alone is not guaranteed to protect you from COVID-19.
Masks are an important tool in the fight against COVID-19, but are not the only one in the tool box. Don’t forget to wash your hands, stay six feet apart from people when you can and avoid large crowds. And be wary of rushed, inaccurate attempts to misconstrue new research.