Melania Trump promotes wearing face masks. Her husband, not so much.

First lady Melania Trump used her platform to promote health officials' recommendation on wearing face masks — though her husband has said he won't wear one.

The first lady on Thursday posted a picture of herself wearing a mask on Twitter, emphasizing the Centers for Disease Control and Prevention's recommendation that Americans wear face masks in public to help slow the spread of coronavirus across the U.S.

“As the CDC continues to study the spread of the Covid-19, they recommend that people wear cloth face coverings in public settings where social distancing measures can be difficult to maintain,” her post said. “Remember, this does not replace the importance of social distancing. It is recommended to keep us all safe.”

The first lady's decision to sport what appeared to be a paper surgical mask appeared to contradict the guidance of Surgeon General Jerome Adams, who as recently as Thursday morning urged Americans to preserve those types of face coverings for health care workers and instead fashion homemade cloth alternatives. "Make your own," the nation's top doctor told "Fox & Friends."

Hospitals around the country have been scrambling to obtain enough personal protective gear as they confront a wave of Covid-19 cases, a highly contagious disease that demands strict protocols from health workers.

On Friday, the president outlined the CDC guidance that encourages the use of cloth masks when outside of the home, and he expressed his preference for scarves as a makeshift face covering.

He also made it clear that he wouldn’t be wearing one.

“I just don’t want to wear one myself. It’s a recommendation. I am feeling good,” Trump said during Friday's coronavirus briefing. “I just don't want to be doing — I don’t know, somehow sitting in the Oval Office behind that beautiful Resolute Desk, the great Resolute Desk, I think wearing a face mask as I greet presidents, prime ministers, dictators, kings, queens. I don’t know, somehow, I don’t see it for myself.”

Former Vice President Joe Biden has urged the president to “follow the science,” adding that he will wear a mask when out in public.

But as the CDC recommends the cloth face coverings, other experts are casting doubt on the effectiveness of healthy people using a mask to protect themselves and others from the virus.

On Thursday, a standing committee of the National Academies of Sciences, Engineering and Medicine issued a response to questions from the White House Office of Science and Technology Policy about the effectiveness of homemade fabric masks.

It is not yet clear whether these masks can stop the transmission of coronavirus, the committee noted, particularly the small particles that are potentially exhaled by asymptomatic or presymptomatic individuals.

“The available evidence is inconclusive about the degree to which homemade fabric masks may suppress spread of Covid-19 from the wearer to others. There are no studies of individuals wearing homemade fabric masks, in the course of their typical activities. Only limited, indirect evidence exists regarding the effectiveness of these masks for protecting others, when made and worn by the general public on a regular basis,” the rapid expert consultation said.

The World Health Organization this week also issued new guidance about using masks, emphasizing that medical masks should be reserved for health care workers. The organization also said it would not be making a recommendation for or against the use of nonmedical masks at this time because the use of homemade masks in the community setting “has not been well evaluated.”

“There is limited evidence that wearing a medical mask by healthy individuals in the households or among contacts of a sick patient, or among attendees of mass gatherings may be beneficial as a preventative measure,” the guidance said. “However, there is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including Covid-19.”

Quint Forgey contributed to this report.