Fact Check Friday: Did a study prove masks are not effective?

Posted at 7:48 AM, Dec 04, 2020
and last updated 2020-12-04 11:18:38-05

A recent study out of Denmark, published in the Annals of Internal Medicine, has been shared tens of thousands of times on social media since mid-November and has many people questioning the effectiveness of wearing masks.

According to – a self-described project of the Annenberg Public Policy Center at the University of Pennsylvania – the Danish study “doesn’t prove masks don’t work against the coronavirus.”

But the site says there were several posts claiming the study showed that masks either provide no protection or don’t work.

The study was a randomized trial from April to May 2020 with roughly 6,000 people who left their homes for at least three hours a day.

Half of the participants were given 50 disposable masks each and were told to wear them. The other half did not get the masks or the recommendation.

After a month, only 11 more people tested positive in the group not wearing masks, which led to the interpretation that masks are ineffective.

An editorial from Dr. Thomas Frieden, former director of the CDC, published alongside the journal entry said “Community mask use can substantially reduce risk for SARS-CoV-2 transmission, especially when enough people use them and when mask use is combined with other effective public health and social measures.”

Frieden also wrote, “Although no single strategy can control the pandemic, widespread masking in the community can mitigate spread as part of a comprehensive approach. Masks have been shown to protect others and, despite the reported results of this study, probably protect the wearer. Maximum benefit of masking is likely to result from the combination of source control and wearer protection. If everyone wears a mask when near others, everyone is safer.”

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