In an editorial piece published in response to a Denmark study published earlier this week, Frieden contended that masks are a significantly better virus mitigation tool than nothing at all. 

"Although no single strategy can control the pandemic, widespread masking in the community can mitigate spread as part of a comprehensive approach,” he wrote. “An N95 mask is better than a surgical mask. A surgical mask is better than most cloth masks. A cloth mask is better than nothing.” 

The study released Wednesday was carried out by researchers at the University of Copenhagen. The study involved nearly 5,000 participants who were separated into two groups: masks-wearers and non-mask wearers. 

In the end, 42 mask-wearers and 53 non-mask-wearers contracted the virus. The team said the study’s results were “inconclusive,” but the researchers later noted that it did not appear that surgical masks played a “statistically significant” role in reducing infection rates. 

Study caveats

In his response to the study, Frieden argued that the study was flawed because it relied on patient reported home tests during a period when infection rates in Denmark were low. Additionally, other virus prevention strategies had already been put into effect. 

Frieden’s belief that masks are an effective virus mitigation strategy is supported by a growing body of evidence from other studies that have found that wearing a mask is one of the most effective tools for protecting oneself and others. 

A report from the CDC released last week concluded that "adopting universal masking policies can help avert future lockdowns, especially if combined with other non-pharmaceutical interventions such as social distancing, hand hygiene, and adequate ventilation." On Monday, NIH director Francis Collins called masks a "lifesaving medical instrument.” 

Frieden agreed that wearing a mask is even more effective when paired with other COVID-19 safety measures. 

“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,” he wrote.