The official advice on whether people should wear face masks to stop the spread of COVID-19 could change, with fresh debate over how effective they could be in the fight against the new coronavirus. 

Despite face masks being widely in use in many East Asian countries, the World Health Organization (WHO) has consistently only recommended they be worn by those who either have COVID-19 symptoms, or their carers, while advocating that they be provided to front-line healthcare workers. 

A WHO panel is now set to assess whether or not they should recommend the general public use them, too.  

At Wednesday's media briefing, WHO Director-General Tedros Adhanom Ghebreyesus, said the "WHO continues to gather all available evidence and continues to evaluate the potential use of masks more broadly to control COVID-19 transmission at the community level."

He added: "This is still a very new virus and we're learning all the time. As the pandemic evolves, so does the evidence and so does our advice."

During the press conference, Ghebreyesus reiterated the WHO's position, that "masks are only effective when combined with other protective measures."

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New Study  

Studies vary on how far the virus, which is largely transmitted via droplets from an infected person, can travel, with one U.S. study claiming that a cough can reach six meters and a sneeze eight meters. 

The report by Massachusetts Institute of Technology (MIT), which is thought to be under consideration by the WHO along with unpublished evidence from Hong Kong, suggests the disease can travel at far greater distances than the organization's current recommendations mitigate for. 

The WHO advocates people keep one meter apart, while the UK and U.S. advise two meters, respectively. 

The MIT team found that exhalation can generate a small moving cloud of gas, containing droplets of liquid, the smallest of which can be carried over long distances. 

The scientists who worked on the study state that their findings show the appropriate wearing of masks, especially indoors or in poorly ventilated rooms, can help reduce the risk of transmission.  

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Still a matter of debate 

Infectious disease specialist, David Heymann, told a Chatham House briefing: "There is right now a debate about the usefulness of masks because Hong Kong has provided some evidence that masks may be useful in protecting individuals from infection.

"It's not clear yet whether or not that's true.

"WHO, the group that I work with, is debating that with a group of experts around the world... to understand whether there is evidence which would call for a change in what WHO is recommending now for masks – which is that they really don't have a major role in protecting people from infection except in healthcare workers, where they also wear eye protection and they also have a role from protecting others from coughs or sneezing."

He added: "But as the evidence becomes available, it seems there will be a debate trying to decide whether masks play a role at some point in the outbreak.

"And believe me, if they do, there is a private sector healthy enough to begin producing those masks in quantities necessary."

Other scientists have been warning that the lack of public use of face masks risks the disease spreading further.

"The big mistake in the U.S. and Europe, in my opinion, is that people aren't wearing masks," Gao Fu, the director of the Chinese Center for Disease Control and Prevention, told Science magazine.

"Droplets play a very important role – you've got to wear a mask, because when you speak, there are always droplets coming out of your mouth."

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A once rare sight in the West, more and more countries are following their Asian counterparts and advising their citizens to wear face masks. Earlier this week, Austrians were ordered to wear face masks while shopping, the U.S. Centers for Disease Control is now assessing their public use, while the Israeli government has already asked its citizens to wear masks once they leave the house. 

Before the epidemic, China had produced about half of the world's masks with a daily output of 20 million. This was upped in early March, official figures putting the tally at 110 million masks being produced per day – many of which are now being exported to those countries now at the center of the outbreak. 

The demand for masks only looks set to rise, especially if the WHO recommends their public use.