The World Health Organisation (WHO) updated its guidance on Friday to recommend that governments ask everyone to wear fabric face masks in public areas where there is a risk of transmission of Covid-19 to help reduce the spread of the pandemic disease.
In its new guidance, prompted by evidence from studies conducted in recent weeks, the WHO stressed that face masks were only one of a range of tools that can reduce the risk of viral transmission, and should not give a false sense of protection.
"Masks on their own will not protect you from Covid-19," the WHO's director-general Tedros Adhanom Ghebreyesus told reporters at a briefing.
The WHO's technical lead expert on Covid-19, Maria Van Kerkhove, said in a Reuters interview: "We are advising governments to encourage that the general public wear a mask. And we specify a fabric mask - that is, a non-medical mask.
"We have new research findings," she added. "We have evidence now that if this is done properly it can provide a barrier ... for potentially infectious droplets."
While some countries and US states have recommended or mandated the wearing of face coverings in public, the WHO had previously said there was not enough evidence for or against the use of masks for healthy people in the wider community. It had always recommended that medical masks be worn by people who are sick and by those caring for them.
Britain has said masks will be compulsory for passengers on buses, trains, aircraft and ferries in England from June 15.
The U.N. agency's advice that all healthcare workers dealing with Covid-19 patients, or with suspected cases of the respiratory disease caused by the novel coronavirus, should wear medical masks remains the same, Van Kerkhove said.
But the advice has been broadened to recommend staff coming into contact with any patients or residents in clinics, hospitals, care homes and long-term residential facilities should also wear masks at all times, she said.