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expert reaction to reported comments from Boris Johnson that they are looking at ways of making sure people wear face coverings in shops

It has been reported that the government are looking at making facemasks compulsory for people when in shops.


Dr Ben Killingley, Consultant in Acute Medicine (Clinical Lead) and Infectious Diseases, University College London Hospitals, said:

“It’s fair to say that our thoughts and attitudes about the role that face masks have to play in combatting this pandemic have evolved over the last few months.

“A lack of evidence of real world effectiveness in the scientific literature and concerns about supply chains led to advice that mask wearing for the general public was not recommended.

“However, this pandemic has brought challenges that have not been faced before. The plans and stockpiles that were in place were based on the occurrence of an influenza pandemic, but the SARS CoV2 pandemic with higher transmission rates, no antiviral treatment and no near prospect of a vaccine, presents a very different problem and the bar so to speak, has been lowered so that anything that might help could be considered if any downsides can be mitigated.

“Indirect evidence to suggest face mask do help reduce the spread of infection is accumulating. Such evidence includes studies showing that masks reduce the dispersal of respiratory secretions and that countries where face mask wearing has been more prevalent have lower infection rates. Wearing masks to protect others is an emerging theme.

“As the country tries to get back to normal and social distancing is relaxed, the value placed in facemasks has risen. In any situation where close (<2m), prolonged (>15 minutes) contact cannot be avoided then facemasks might help; wearing masks on public transport fits this description. Going further to recommend mask use for brief but frequent close contact situations, e.g. supermarkets, is consistent with the further attempts at risk mitigation the government is pursuing. This is largely an evidence free zone, but with masks supplies much more assured and much greater public acceptance of mask wearing the downsides of mask use seem small. So, mask use looks set to stay and become a new norm.

“Caution though is needed not to overplay the potential benefit of masks at the expense of other things have been proven to help such as hand hygiene.”


Prof Paul Hunter, Professor in Medicine, UEA, said:

“The Prime Minister is right if he is reviewing England’s position on facemasks. It must be said that the value of facemasks in the community is still an issue that the scientific community has not yet reached consensus on. In part this lack of consensus is due to the different emphasis given to different types of study. Randomised controlled trials (the gold standard of scientific evidence) of facemask use in the community have not proven that mandating their widespread use is protective. Other types of study have given mixed results, some finding no benefit and others like case control studies generally finding them to be protective. Two recent studies, one our own and one by Brauner and colleagues from Oxford University found that face covering mandates have had little impact on the spread of COVID-19 in those countries that implemented them, though as we both accept the data quality for this is poor so no firm conclusions on this issue can be drawn. Unfortunately, it is unlikely that this debate will be resolved anytime soon.

“In our own review, published in March, we concluded that although the evidence was not sufficiently strong to support widespread use of facemasks as a protective measure against COVID-19, we did think that there was enough evidence to support the use of facemasks for short periods of time by particularly vulnerable individuals when in transient higher risk situations. The PM is right to say he does not want a world where everyone has to wear face coverings the whole time everywhere. This would have little if any value and this could also pose additional risks.

“The current requirement to wear face coverings on public transport is one such example of a transient higher risk situation. Their use in shops may also be another example if it is not possible to maintain social distancing. However, if it is mandated to wear them in shops this raises the issue of whether they should be mandated in other contexts. One such context would be pubs and bars where the risk of transmission is arguably much greater than in shops. Face coverings could not be safely used in any establishment that people go to eat and drink. The constant need to be always moving your face covering to take a sip of beer could be a risk.

“Whatever is eventually decided it is vitally important that any policy change is supported by a strong public health education campaign. People will need to know what designs and materials of mask are appropriate, how to wear them properly, how long they should wear them for, and how they should either safely dispose of them or wash them ready for reuse. Materials need to be sufficient to block dispersion of virus and not get too damp in use, they need to cover both the mouth and nose and fit snugly to the face. People should not wear the same mask all day, 5 hours is probably the longest. Worn masks must be disposed of safely to avoid infecting someone else who picks it up and they should be washed before using again. All too often you see people wearing a mask in a way that is not going to achieve much. People do not need to wear masks while walking or exercising outside and wearing masks when taking exercise could be counterproductive. The balance of evidence is that the N95 respirator masks do not provide any additional benefit for people in the community and many cause problems if warn for any period of time. In particular people should not wear N95 respirator masks when exercising.

“The most important thing, however, is that anyone wearing a mask must not assume that they are automatically protected. People should still practice distancing and continue to wash their hands.”


Prof David Heymann, Professor of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, said:

“Face masks protect others from infection by catching virus-containing droplets when a person who is infected and has a high level of virus in the nasal passage speaks, shouts, sings, coughs or sneezes. Face masks should be worn when physical distancing cannot be assured from others such as by carers in care homes and by people serving others who are physically distancing but who because of their work cannot physically distance from them. They should also be worn by all people in a situation where no one can physically distance to prevent infection of others – especially in closed spaces such as public transport.

“Face masks do not substitute for physical distancing if physical distancing is possible, and they do not protect the wearer from infection unless they are worn as part of personal protective equipment that also protects the eyes, a potential site of infection.”


Dr Antonio Lazzarino, Department of Epidemiology and Public Health, UCL, said:

How strong is the evidence on the effectiveness of face coverings in reducing transmission of SARS-CoV-2?

“The evidence has not changed in the last few weeks; it’s still extremely weak. The question is why politicians may be changing their minds now. My worry is that masks are a pretense to ease the lockdown to help the economy. But this may well happen at the expense of people’s health. Lockdown is the only measure that is proven to work.

Are face coverings as important as e.g. hand washing and social distancing?

“There is no research in this area. What’s clear is that wearing a mask is not compatible with having uncontaminated hands, as it is practically impossible not to touch your mask. So the question about which one is more important is extremely relevant and needs to be addressed.

Any other comments on the suggestion the government may be thinking about making them mandatory in shops?

“Close places should be avoided. We don’t know if – for example – 1m distance with masks is safer than 2m without. If masks make people get closer, they may be dangerous.

“One more point: whatever the effect of masks is, this measure was taken too late, as the epidemic is falling down already. We cannot assess the effectiveness of measures taken at this stage of the outbreak.”


Prof Adam Finn, Professor of Paediatrics, University of Bristol, said:

“We know that at least some transmission of SARS CoV2, like many other viruses, occurs in droplets generated by coughs and sneezes and we know that covering your nose and mouth impedes at least some of those droplets from shooting across the space between you and someone else nearby who might breath them in. So we can be confident that wearing face coverings in crowded places will reduce the likelihood of that happening. The more efficient the face covering is at catching the droplets, the better it will work.

“So if you are in a shop and everyone else is wearing a mask, you should feel safer than if they aren’t.

“Most masks will do a much less efficient job of protecting the wearer from breathing in droplets and no mask will stop you infecting yourself with your hands – in fact if you spend a lot of time touching and adjusting your mask and your hands are contaminated, they could even increase your risk of self inoculation.

“So wearing masks is all about protecting others – especially if you are a young person, because young people are much more likely to have the infection without realising.

“Keeping your hands clean protects you from infecting yourself and from infecting others by touching things with contaminated hands that others might then touch.

“If we all get used to wearing masks and keeping our hands clean then it will be easier to keep the virus under control while resuming a more normal life. It’s a small price to pay if it helps to enable us all resume work, play, shopping and seeing our friends isn’t it? As so often in life, by being considerate towards others we actually help ourselves.”



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


Declared interests

Prof Adam Finn: “No conflicts.”

None others received.

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