CNN  — 

President Donald Trump said Thursday his administration will soon release nationwide recommendations on wearing face masks after initially telling Americans they weren’t necessary to prevent the spread of coronavirus.

But a top health adviser on his team strongly cautioned that masks should not lull Americans into a false sense of security that would lead them to abandon social distancing guidelines that the White House has encouraged to slow the spread of the coronavirus as the death toll in the United States rises.

Speaking at a White House task force briefing, Trump said the new guidance would stop short of requiring all Americans to wear face coverings.

“I don’t think they’ll be mandatory because some people don’t want to do that,” he said, adding that Americans who do want to wear face coverings can “decide for themselves.”

He repeated his assertion that fabric coverings like scarves would be preferential, both because they avoid use of medical-grade masks needed in hospitals and because of their thickness.

“In many ways, a scarf is better. It’s thicker,” he said.

Though he was addressing what citizens should do, Trump’s claim that scarves can work better than masks is not supported by the Centers for Disease Control and Prevention’s guidance to health care workers. While scarves may offer some protection, the CDC’s advice describes scarves as a possible last resort if masks are not available.

When masks are no longer available, the CDC says, workers “might use homemade masks (e.g., bandana, scarf) for care of patients with COVID-19 as a last resort.” The guidance also states that “caution should be exercised when considering this option” and that face shields should be used in addition to these homemade masks.

Trump did not offer timing on the new recommendations, but people familiar with the matter said the administration was working Thursday to complete the guidance, which would advise Americans to use a face covering when leaving their homes.

Vice President Mike Pence said the task force was still weighing recommendations from the Centers for Disease Control and Prevention and would issue recommendations in the next several days.

CNN reported on Wednesday that most members of the task force have come to agree that Americans should begin wearing face coverings in public and could issue formal guidance on the matter soon.

Some members of the task force – including Dr. Deborah Birx – have cautioned in meetings against recommending Americans wear masks because of a fear it could lull them into a false sense of protection and prevent them from socially distancing. But new insights into asymptomatic spread of the virus have led to a reconsideration of the guidance.

Speaking at the briefing on Thursday, Birx said White House officials were still debating new recommendations.

“It is not a substitute for the presidential guidelines (on social distancing) that have already gone out,” she said. “Don’t get a false sense of security that that mask is protecting you exclusively from getting infected.”

“This worries us,” she added. “That’s why the debate is continuing about the mask.”

Among the issues discussed by the task force and the CDC have been how to teach Americans to wear masks and how to prevent a rush on medical-grade equipment, such as N95 respirators, still in short supply for hospitals.

There have also been discussions of the cultural shift that recommending masks would represent, since Americans (unlike citizens of some Asian countries) are not accustomed to wearing masks in public.

And there has been some consideration of whether or not to call the recommended face coverings “masks.” Some have suggested referring to them simply as “face coverings” or “courtesy masks” to distinguish them from the medical masks needed by professionals.

CNN’s Daniel Dale contributed to this report.