GENEVA — Governments in areas with widespread COVID-19 transmission should encourage the use of non-medical masks on public transport, in shops and in other locations where physical distancing is difficult, the World Health Organization (WHO) recommends, in updated guidance published on Friday. Additionally, people over 60, or who have underlying health conditions, should wear medical masks in these settings, while all workers in clinical areas of health facilities should also use them — not just those who deal with COVID-19 patients. However, WHO chief Tedros Adhanom Ghebreyesus warned against putting too much faith in masks, stressing that they are only part of a comprehensive strategy to defeat the disease. “I cannot say this clearly enough: masks alone will not protect you from COVID-19,” he told journalists. “Masks are not a replacement for physical distancing, hand hygiene and other public health measures.” Three layers of protection WHO issued the updated guidance following a review of available evidence and extensive consultation with international experts and civil society groups. It contains new information on the composition of fabric masks and other face coverings, based on research commissioned by the UN agency. Masks can be purchased or homemade, and should contain three layers: ideally a cotton lining, a polyester outer layer, and a middle “filter” made of polypropylene, or some other non-woven material. “With those three layers, and in that combination, that fabric can actually provide a mechanistic barrier that if someone were infected with COVID-19, it could prevent those droplets going through and infecting someone else,” said Dr. Maria van Kerkhove, a WHO epidemiologist. Sick? Stay home! WHO continues to recommend that anyone with COVID-19 symptoms should stay home and seek medical help. People caring for them should wear a medical mask when they are both in the same room. “If it is absolutely necessary for a sick person or a contact to leave the house, they should wear a medical mask,” said Ghebreyesus. Meanwhile, confirmed COVID-19 patients should still be isolated and cared for in a health setting, while all their contacts should be quarantined. — UN News