The Centers for Disease Control and Prevention will advise all Americans to wear cloth masks or other face coverings if they go out in public but President Donald Trump said the new guidelines will not be mandatory.

But the policy marks a profound change in messaging as both the CDC and World Health Organization previously said people don't need to wear masks unless they are sick.

The new guidance has not been officially announced but it is in the works, according to multiple reports, which comes as more than 1 million people globally have been infected with the coronavirus.

President Trump confirmed it was on the way.

'I think they're going to be coming out with the regulations on that,' he said Thursday at his daily White House coronavirus briefing.

'I don't think it will be mandatory because some people don't want to do that, but if people wanted to wear them, they can. People wanted to use scarves, which they have that many people have of them, they can. In many cases, the scarf is better, it's thicker. Depending on the material, it's thicker. But they couldn't do that if they want. The recommendation is coming out and we'll see what that recommendation is but I will say this, they can pretty much decide for themselves right now,' he said.

Vice President Mike Pence noted it would be coming out 'in the days ahead.'

Donald Trump's administration is encouraging all Americans to wear cloth masks or other face coverings if they go out in public

The CDC will urge people to wear cloth masks and not surgical masks, which are desperately needed by health care workers

Health officials believe wearing masks would reduce the risk of people not showing symptoms from spreading the virus.

Dr. Deborah Birx, who coordinates the day-to-day administration response to the virus, cautioned people should not consider masks as a guarantee of protection.

'We don't want people to feel like I'm wearing a mask, I am protected, and I'm protecting others. You may be protecting others, but don't get a false sense of security that that mask is protecting you exclusively from getting infected because they were other ways that you can get infected because the number of asymptomatic and mild cases that are out there,' she said at the White House briefing.

She advised people to continue social distancing practices and to wash their hands.

The new guidance will make it clear that N95 surgical masks should be saved for health care workers and others on the front lines, who have been in dire need of them.

Simple cloth masks - or scarves or bandannas - will be the recommendation for when people go to the grocery store, for a walk or are outside.

'In light of these new data, along with evidence of widespread transmission in communities across the country, CDC recommends the community use of cloth masks as an additional public health measure people can take to prevent the spread of virus to those around them,' according to a copy of the guidance obtained by The Washington Post.

While people wearing masks are common in Asian countries - especially in large cities where air quality is poor - it would be a stark sight on the streets of America.

A leading member of the National Academy of Sciences (NAS) and former Harvard School of Public Health dean, Dr Harvey Fineberg, told CNN that while surgical masks should be reserved for health care workers, he himself is going to be wearing a bandanna or other face covering.

Dr Anthony Fauci, a White House coronavirus task force member and leading infectious disease expert had said that the subject of having Americans cover their faces in public is a 'very active discussion' among the committee.

Research remains mixed on whether surgical masks work as well as N95 respirators and whether cloth face coverings do much at all to prevent infection, but Dr Fauci noted that they might be protective, and certainly wont do harm - as long as medical workers have enough.

More Americans may need to cover their faces as experts warn breathing and talking may spread coronavirus

'From what I've seen...I think that if we do not have the problem of taking away masks from healthcare workers who need them, I would lean towards it because I think that it - I mean, what - what harm can it do if you have enough masks?' Dr Fauci told CNN.

Like most respiratory illnesses, coronavirus is spread in tiny droplets of moisture that carry virus particles.

The CDC warns that are expelled when sick people cough or sneeze.

However, talking can send the droplets into the air too, Dr Fineberg told CNN. Even the breathe of a person with coronavirus could be dangerous.

Dr Harvey Fineberg said he's going to start wearing a mask in public (left). Dr Anthony Fauci (right) said that US officials are having 'very active discussions' about telling Americans to wear face coverings in public

'While the current [coronavirus] specific research is limited, the results of available studies are consistent with aerosolization of virus from normal breathing,' Dr Fineberg said.

The NAS letter to the White House noted research conducted in a Chinese hospital that found the virus can sent into the air and linger there when health care workers take of their protective gear and possibly as result of cleaning jostling the particles free, or even of movements.

Americans are now advised to stay more than six feet apart from one another to slow the spread of coronavirus, but studies from the University of Nebraska and Massachusetts Institute of Technology (MIT) found that the virus can travel much further.

'If you generate an aerosol of the virus with no circulation in a room, it's conceivable that if you walk through later, you could inhale the virus,' Dr Fineberg said.

'But if you're outside, the breeze will likely disperse it.'

Dr Fineberg said he himself will begin wearing a mask in public as a precaution against contracting the virus, especially in relatively closed spaces like grocery stores.

'I'm not going to wear a surgical mask, because clinicians need those,' said Dr Fineberg, who is former dean of the Harvard School of Public Health.

'But I have a nice western-style bandana I might wear. Or I have a balaclava. I have some pretty nice options.'

Reports have emerged that the CDC - and the White House, as Dr Fauci disclosed - are considering