CDC Recommends Community Use of Multilayered Cloth Masks to Control COVID-19 Spread

A new scientific brief published by CDC on Nov. 10 recommends the community use of non-valved multilayer cloth masks to control the spread of COVID-19. According to the agency, masks are primarily intended as source controls to reduce the emission of potentially virus-laden respiratory droplets generated when people cough, sneeze, sing, talk, or breathe. CDC describes cloth masks as also providing some personal protection for wearers. The agency stresses that the community benefit of the use of cloth masks to prevent transmission of SARS-CoV-2 is due to a combination of these effects.

“The relationship between source control and personal protection is likely complementary and possibly synergistic, so that individual benefit increases with increasing community mask use,” CDC’s website states.

The brief lists observational and epidemiological studies that examine the “real-world” effectiveness of community masking. For example, an investigation of a case in which two symptomatic hairstylists interacted with 139 clients for an average of 15 minutes each over eight days found none of the 67 clients who consented to testing developed an infection. The stylists and clients all wore masks as required by local ordinance and company policy.

Seven studies concerning a variety of communities—including a Massachusetts hospital system, the German city of Jena, and a panel of 15 U.S. states plus Washington, D.C.— “confirmed the benefit of universal masking in community-level analyses,” CDC says. The agency also describes an economic analysis using U.S. data which found that increasing universal masking by 15 percent could reduce lockdown-associated losses of up to $1 trillion, or about 5 percent of the U.S. gross domestic product.

CDC states that further research is needed to expand the evidence base for the protective effect of cloth masks, particularly to determine the most effective combinations of materials. The agency concludes that universal masking policies can help avert future lockdowns, especially if combined with measures like social distancing, hand hygiene, and adequate ventilation.