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expert reaction to new WHO advice on use of facemasks in the context of COVID-19

The World Health Organisation (WHO) has issued guidance on the use of facemasks in the context of COVID-19.


Prof Trish Greenhalgh, Professor of Primary Care Health Sciences, Nuffield Department of Primary Care Health Sciences, University of Oxford, said:

“At this time of critical shortages of medical masks, it makes sense for these masks to be reserved for frontline healthcare workers who are at much greater risk than the public (and of course, if your doctor or nurse is incubating COVID-19, they could pass it to you). But masks are relatively easy to manufacture, and many clothing  companies have offered to repurpose their facilities to produce masks and other protective equipment, so we should perhaps start to consider whether the public should be encouraged to wear masks once supplies have been topped up.

“The research evidence on the wearing of masks by the lay public is interpreted differently by different official bodies. The US Centers for Disease Control and Prevention, for example, also changed its guidance on 6th April ( and now says the following:

“Cover your mouth and nose with a cloth face cover when around others

  • You could spread COVID-19 to others even if you do not feel sick.
  • Everyone should wear a cloth face cover when they have to go out in public, for example to the grocery store or to pick up other necessities.
    • Cloth face coverings should not be placed on young children under age 2, anyone who has trouble breathing, or is unconscious, incapacitated or otherwise unable to remove the mask without assistance.
  • The cloth face cover is meant to protect other people in case you are infected.
  • Do NOT use a facemask meant for a healthcare worker.
  • Continue to keep about 6 feet between yourself and others. The cloth face cover is not a substitute for social distancing.”

“Indeed, the WHO itself, in a different set of guidance (on pandemic influenza), acknowledges that there may be situations where the balance of probabilities falls in favour of masks. I quote from their guidance,

“Face masks worn by asymptomatic people are conditionally recommended in severe epidemics or pandemics, to reduce transmission in the community”

“My own assessment of this complex literature is that a) we don’t know for sure whether masks would help; b) a key argument against them seems to be that the public can’t be trusted to follow instructions for how to fit and wear them properly, which is a bit patronising in the current circumstances; and c) we don’t currently have enough masks. An argument in favour of masks is that people may well be highly motivated to learn the proper techniques for wearing their masks properly. Even a small beneficial effect might make a difference at this difficult time, when fatality rates are rising fast and health systems under unprecedented strain.”


Dr Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading, said:

“This welcome review by the WHO of the current data concludes that there is no evidence to suggest that face mask wearing in the community, by healthy people, can protect them from infection with respiratory viruses, including the one causing COVID-19.  They go on to point out that such inappropriate use of masks could lead to a false sense of security and cause people to neglect other, essential hygiene and distancing measures.  The advice remains that anyone with symptoms should wear a mask, but the UK goes beyond that by telling infected people to stay at home.  It remains the case that your front door will contain the virus much more effectively than any face mask.”


Prof William Keevil, Professor of Environmental Healthcare, University of Southampton, said:

“Following on from my previous comments about my concerns over the public wearing face masks I believe the new WHO Advice is the correct strategy. There are many loose fitting surgical facemasks on sale made of poor quality materials which wet easily from breath moisture and provide inadequate filtration. Even wearing Class 2 or 3 surgical face masks brings problems of fitting them correctly and ensuring their safe removal and placing into an appropriate double bag container for disposal. Which should be immediately followed by washing hands. The untrained public can be regularly seen on television continuously touching and readjusting the masks, contaminating their hands and risking contacting their eyes. Indeed, what is the point of wearing a mask if you also do not protect your eyes, a known route for virus entry, as healthcare professionals do by wearing goggles and/or a full face visor.  Even wearing an approved N95 (FFP2) or N99 (FFP3) respirator brings problems for the public of how to fit them and dispose of them safely. Moreover, some designs have a valve which open for exhalation of moist breath which can wet the inside of the mask, and allow better exit of carbon dioxide; these masks may give some protection for the wearer but do not protect anyone in the close vicinity if the mask wearer is shedding virus.  High quality face masks and ventilators, as well as other items of PPE, can be difficult for healthcare professionals to obtain and these essential resources should be reserved for these highly trained professionals who know how best to wear them. The 2-metre distancing rule should continue to be followed, as well as current self-isolation guidance, and needless to say: wash hands rigorously and frequently with soap and warm water, or failing that use an alcohol hand gel containing more than 60% alcohol with 70-80% preferred.”


All our previous output on this subject can be seen at this weblink:


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