WASHINGTON — The Trump administration is close to recommending that all Americans wear cloth masks if they go out in public, a change in position that reflects new concerns that the coronavirus is being spread by infected people who have no symptoms and new data suggesting the United States is not yet slowing the rate of infections.

At a White House briefing Thursday evening, both President Trump and Vice President Pence said that new guidance on masks would be issued by the Centers for Disease Control and Prevention in the coming days.

“If people want to wear them, they can,” President Trump said, declaring that while the administration was “coming out with regulations” on mask wearing soon, whether to follow them was a personal choice.

is expected to recommend Americans wear masks in public.

Her caveats on masks reflect what has been a common view among many public health bodies about the effectiveness of masks for the general public.

Until now, the C.D.C., like the World Health Organization, has advised that ordinary people don’t need to wear masks unless they are sick and coughing.

Part of the reason has been to preserve medical-grade masks, including N95 respirator masks, for health care workers who desperately need them at a time when they are in continuously short supply.

Public health officials have continued to stress, however, that N95 masks and surgical masks should be saved for front-line doctors and nurses, who have been in dire need of protective gear.

“They are NOT effective in preventing general public from catching #Coronavirus, but if health care providers can’t get them to care for sick patients, it puts them and our communities at risk!”.

Trump said that broad use of nonmedical masks, at least, was “certainly something we could discuss.”.

Citing new data that shows high rates of transmission from people who are infected but show no symptoms, he said the guidance on mask wearing was “being critically re-reviewed, to see if there’s potential additional value for individuals that are infected or individuals that may be asymptomatically infected.”

Both papers recommended that members of the public wear homemade cloth masks, to preserve limited supplies of surgical masks and higher-grade respirators for health care workers

“It is critically important that public adoption not come at the expense of medical mask availability for health workers,” said Jason Abaluck, an associate professor of economics at the Yale School of Management and a co-author of the paper