Federal officials debating whether to recommend that face coverings be routinely worn in public are responding to increasing evidence that infected people without symptoms can spread the coronavirus, according to internal memos provided to the White House by the Centers for Disease Control and Prevention.

Simple cloth masks that cover the mouth and nose can prevent virus transmission from such individuals when they are out buying groceries or seeking medical care, according to the memos obtained by The Washington Post.

But the documents note that widespread public use of masks is not culturally accepted in the United States the way it is in many Asian countries, where face coverings helped reduce the spread of the virus.

The memos were drafted in recent days by the CDC and sent to officials at the Department of Health and Human Services and the White House coronavirus task force for consideration of masks as an additional measure to slow the pandemic.

If adopted by the coronavirus task force, the recommendations would represent a major change in official CDC guidance that healthy people don’t need masks or face coverings. The memos make clear the coverings under discussion are not medical masks, such as N95 respirators or surgical face masks, which are needed by front-line health-care workers and are in extremely short supply.

The office of the vice president, which is overseeing the task force, did not immediately return a request for comment.

At a White House briefing Tuesday, President Trump was asked about people using face coverings. “My feeling is there is no harm in using a scarf or something,” he said, adding that medical masks should be reserved for hospitals. “I would say do it. You wouldn’t have to do it forever."

According to the CDC and World Health Organization, only the sick, and their caretakers, should wear face masks. Research scientist Jeremy Howard disagrees. (The Washington Post)

Wearing cloth masks in public places would be an additional community mitigation tool, according to the memos. Social distancing of at least six feet is still recommended even when wearing a mask. The memos emphasize that a cloth facial mask is intended not so much to protect the wearer but to help prevent the spread of the virus to others. A memo dated Thursday noted that people “generate respiratory aerosols when speaking, coughing and sneezing” that can be inhaled by nearby individuals.

That and a more recent memo dated Monday refer generally to increasing evidence that people can spread the virus even when they feel well, often referred to as pre-symptomatic and asymptomatic transmission.

A CDC report last week on asymptomatic infections among residents at a skilled nursing facility in the Seattle area found that of 23 residents who tested positive for the novel coronavirus, 13 were asymptomatic or pre-symptomatic on the day of testing.

Infectious-disease experts say asymptomatic transmission may be playing a larger role in the outbreak than previously thought, but just how big remains unknown. Studies are underway at the CDC and elsewhere to better understand such spread.

One of the challenges is figuring out what to call any face covering. In the earlier memo, one suggestion was to refer to it as a Courtesy Mask or Universal Source Control.

That memo says face covers should extend above the nose and below the chin to “completely cover the mouth and nostrils.” It should also fit snugly against the sides of the face and be secured with ties or ear loops, and be composed of multiple layers of fabric but not be “overly restrictive to breathe through.” An ideal face cover can be cleaned in a washing machine and machine dried without damage or distorting its shape, the memo said.

Deborah Birx, the White House coronavirus response coordinator, initially resisted the idea of universal mask use because of concerns that recommending face coverings might undermine messages that people should stay at home as much as possible, according to a person with knowledge of the discussions who spoke on the condition of anonymity because he wasn’t authorized to talk about the issue.

Trump adviser and son-in-law Jared Kushner and others like the idea of recommending face coverings for when people are in public, the individual said.

With covid-19 cases still climbing sharply in the United States, some scientists, health experts, pundits and social influencers have begun vigorously advancing their position that everyone venturing into public or crowded places should wear a mask or face shield — even a homemade one — to lower the rate of transmission of the coronavirus, which causes covid-19.

There’s still no consensus in the scientific community on whether widespread use of such coverings would make a significant difference, and some infectious disease experts worry that masks could lull people into a false sense of security and make them less disciplined about social distancing.

The Monday document suggested promotional “tag lines” the government could use if it recommended face coverings for the public: “COVID ends with me,” “My mask protects you and your mask protects me” and “I wear my mask to protect my community.”

The document noted that recommending widespread use of face coverings “may pose a challenge to U.S. communities because mask-wearing is uncommon,” according to the memo dated Monday.

Still, it said, “in many international communities, wearing masks in public is common, widely considered to be good hygiene, and is seen as a communal gesture of protecting others from the wearer’s potentially infectious exhales.”