Health experts dispute conservatives’ claim that new study finds masks are ineffective

Mask-wearing has remained a hot-button political issue even as more states, including those with Republican governors who long resisted such measures, are adopting mask mandates as case numbers rise across the United States. Numerous studies have found that masks, and perhaps even the mandates, reduce the risk of transmission.

“Masks have been shown to protect others and, despite the reported results of this study, probably protect the wearer,” former Centers for Disease Control and Prevention director Tom Frieden wrote in an editorial that laid out what he sees as the various limitations of the study.

In the large, randomized study published Wednesday in the Annals of Internal Medicine, researchers observed more than 6,000 people in Denmark from April to June when mask-wearing was not required in the country. Fewer people in the group that was advised to wear masks contracted the virus — or about a 14 percent reduced risk because of mask-wearing — but the difference was not statistically significant, indicating that the recommendation to wear the medical masks issued was not particularly effective at preventing the wearers from being infected.

Other experts, however, argue that the study was conducted when there was relatively less community spread of the virus and that testing the participants’ antibodies cannot reliably measure whether they had the virus during the time of the study. ...