President Donald Trump’s coronavirus task force on Friday announced new CDC guidelines urging Americans to wear masks or other protective facial cloth to prevent the spread of the coronavirus, but the president himself repeatedly stressed that the measure is “voluntary” and noted that he wouldn’t be wearing one.

“You can do it, you don't have to do it,” Trump said of the “voluntary public health measure” in a briefing Friday. “I'm choosing not to do it, but some people may want to do it and that's OK. It may be good. Probably will.”

The decision to announce the new recommendation, first reported by Stat News, had been delayed, in part, by fears inside the White House over the optics of issuing new guidelines that directly contradicted those previously pushed out by the federal government, those same sources said. In internal deliberations, members of the administration’s coronavirus taskforce had worried that changing the messaging on masks could raise questions about whether the government made a mistake in its original guidelines, officials say.

Officials were also concerned that the new guidelines would end up worsening the supply problems for healthcare workers who are already running low on personal protective gear, including N95 respirators. As such, the administration's guidance is likely to encourage people to make their own masks at home, an official said.

On February 29, the country’s top doctor, Surgeon General Jerome Adams, posted a disclaimer on Twitter, asking Americans to stop buying masks. “ They are NOT effective in preventing general public from catching #Coronavirus,” he said, adding that healthcare workers needed them to remain in the supply chain so they could more safely treat coronavirus patients. And the Centers for Disease Control and Prevention has said that Americans do not need to wear masks unless they are sick and coughing or if they are taking care of a person with coronavirus.

A barrage of recently published scientific studies say otherwise. And Trump’s coronavirus task force, including officials from the CDC, have for weeks been looking at some of those papers that say the coronavirus can be spread by individuals who do not show symptoms through liquid droplet transmission.

In an email to The Daily Beast, Arleen Porcell, a spokesperson for the CDC said the agency had not yet changed its guidelines on face masks while acknowledging that they were evaluating the data.

“CDC is always evaluating emerging scientific evidence and making guidance updates as needed to keep the American public safe,” she said.

One of the papers being reviewed by the task force—which was written by doctors in Germany and funded in part by the European Union—says the coronavirus can present like the common cold and that the virus can spread “through pharyngeal viral shedding at a time when symptoms are still mild and typical of upper respiratory tract infection.” Other studies being reviewed by the task force and the CDC suggest that the coronavirus might shed through liquid droplets from our mouths and noses when speaking —or singing—around others

In recent days, a slew of doctors, in opinion pieces and on social media, have pushed for the federal government to implement the universal mask policy, arguing that while strict social distancing guidelines do help contain the virus, the use of masks or paper cloths across the nose and mouth could significantly decrease transmission. It shouldn’t be the case that just individuals who are sick wear protective coverings, doctors say. Now that scientists know the virus spreads through asymptomatic or presymptomatic people, they, too, should wear masks.

Despite the overwhelming number of studies looking at the issue and medical professionals calling for the universal use of face masks, officials on the task force and within the CDC debated whether the data available on asymptomatic and presymptomatic transmission was enough to move the needle. A recent report from Singapore re-published on the CDC website said presymptomatic transmission “might occur through generation of respiratory droplets” and “possibly through indirect transmission.” The lack of clear language, officials said, worried the scientists and academics on the taskforce who sought to obtain more convincing reports before moving forward.

Dr. Jeffrey Klausner, an adjunct professor of epidemiology at the University of California Los Angeles who previously worked for the CDC, said that there was “no new evidence” of the benefit of encouraging mask wearing.

“The response to the epidemic is driven by panic and politics,” said Klausner. “The same way we saw recent FDA approval for some medications that have not had demonstrated scientific benefits. There’s been active discussion and pushback from public health experts and politics. Politicians are saying ‘what’s the harm,’ but public health experts are saying ‘what’s the benefit.’ None, based on scientific evidence.”

Klausner and others pointed to the serious shortage of masks available for even healthcare professionals encountering infected patients as a downside to a policy shift. But Dr. David Larsen, an associated professor in the Department of Public Health at Syracuse University, said in a statement on Tuesday that “there is as much evidence for face masks as there is for social distancing.”

“We are rightfully closing our schools, shuttering our businesses, and disrupting our social lives,” said Larsen. “We need to bring anything that can work to the fight, and face masks may help.”