Wearing a mask can help protect you, not just those around you, from coronavirus transmission, the U.S. Centers for Disease Control and Prevention said in new guidance Tuesday. The statement was an update to previous guidance suggesting the main benefit of mask wearing was to help prevent infected people from spreading the virus to others.
Cloth masks act as “source control” to block virus particles exhaled by the wearer and provide “filtration for personal protection” by blocking incoming infectious droplets from others, the CDC said in its new guidance.
The new guidance cites a number of studies showing that masks reduce the risk of transmitting or catching the virus by more than 70% in various instances. One study revealed mutual mask-use helped prevent two infected hair stylists from transmitting the virus to 67 clients who were later interviewed. Another followed infected people who spent more than 10 hours on flights without infecting other passengers when masks were used.
In several scenarios, when officials told people to wear masks, infections and deaths fell significantly, the CDC pointed out.
“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,” the CDC said.
The agency cited an economic analysis that found a 15% increase in universal masking could prevent losses of up to US$1 trillion.
“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 said.
Some cloth masks are nearly as good as surgical masks at blocking droplets, the CDC said. Polypropylene may generate a static charge that captures particles, the CDC said, while silk might repel moist droplets and be more comfortable.
“Multiple layers of cloth with higher thread counts have demonstrated superior performance compared to single layers of cloth with lower thread counts, in some cases filtering nearly 50% of fine particles less than 1 micron,” the CDC said.
“It’s a two-way street,” Dr. Anthony Fauci, National Institute of Allergy and Infectious Diseases director, said Tuesday on MSNBC. “You protect others, their mask protects you, and your mask also protects you.”