Breaking from its tentative recommendations on mask use thus far, the Centers for Disease Control and Prevention said on Tuesday that using masks benefits wearers, which is a step beyond its previous declaration that said wearing masks would only protect those around them.
“Experimental and epidemiological data support community masking to reduce the spread” of the virus, the C.D.C. said in a document that details scientific evidence supporting mask use. “Individual benefit increases with increasing community mask use,” it said.
The unequivocal statements are a departure from the agency’s previous language, which suggested that “the latest science may convince” Americans to wear masks and that mask use could prevent an infected person from spreading the virus to others. “The main protection individuals gain from masking occurs when others in their communities also wear face coverings,” it said.
The agency also offered an economic argument, saying that increasing the proportion of people who wear masks by 15 percent could prevent the need for lockdowns and cut associated losses of up to $1 trillion, or about 5 percent of gross domestic product.
The new document listed several studies that “have confirmed the benefit of universal masking,” as well as some observational studies that have given evidence of its usefulness, including an example of two masked hair stylists who had been experiencing symptoms but did not transmit the virus to any of their 67 masked clients who were later contacted. The document also referred to a study of 124 Beijing households in which mask use significantly cut transmission of the virus, and an outbreak aboard the U.S.S. Theodore Roosevelt in which face coverings appeared to have reduced risk of infection by 70 percent.
Experts said they were thrilled to see the change in the C.D.C.’s stance, and particularly the emphasis on face coverings that protect wearers.
“That matters for public-health messaging, because we don’t have people yet who are completely convinced about the benefits of masking until they see the C.D.C. say that it also protects you and your family,” said Dr. Monica Gandhi, an infectious-disease expert at the University of California, San Francisco.
“I would encourage every American to adhere to masking guidelines now that we hear more clearly today that this will protect you and others,” Dr. Gandhi said. “We cannot afford more lockdowns, but we can do our part to stop Covid-19 transmission and disease.”