Expert comments about face coverings and COVID-19

Some further comments on face coverings and COVID-19 following comments made about face coverings and their potential role in the lifting of lockdown restrictions in this evening’s Government press conference.

The SMC has issued several other Roundups on this topic: on April 28th, April 22nd, April 7th, April 6th, April 3rd, April 3rd (second set) and April 2nd.

Prof Robert West, Department of Behavioural Science and Health at UCL, and Prof Susan Michie, Director of the UCL Centre for Behaviour Change, UCL, and Fellow of the Academy of Medical Sciences, said:

“We are just completing a rapid review on face masks led by Olga Perski that we think brings together the relevant evidence on face masks in community settings (not health and social care settings) and uses a Bayesian approach to assess directly the relatively likelihood that they confer benefit or harm.  The conclusion is that randomised controlled trial evidence is almost completely equivocal on the issue of benefit versus harm on laboratory or clinically confirmed respiratory infections.  We therefore have to rely on judgements.

“Some health experts are using the ‘it stands to reason’ argument that face masks will confer a benefit but in community settings there are genuine risks that have to be considered.  One of these is false reassurance which may lead people to fail to adhere to other personal protective behaviours (i.e. physical distancing, using tissues to catch coughs and sneezes, hand-cleansing, disinfecting surfaces and objects, not touching eyes, nose or mouth).  Johnson’s remarks about face masks “giving people confidence they can go back to work” goes against sensible scientific advice and are unhelpful in potentially fostering precisely the false reassurance we need to avoid.”

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

“The Prime Minister’s hint that the government may be about to recommend face coverings as the country begins to come out of lockdown comes not a moment too soon.  The Office for Budget Responsibility has estimated that lockdown reduces our national economic output by almost one-third.  Many people who are staying at home simply cannot work – and thousands have already lost their jobs either temporarily or permanently.  It is imperative that we use all possible measures to help get society up and running again – back to work, back to contributing to their communities and back to visiting and supporting their older relatives.  One such measure is covering our faces when we are in crowded places such as supermarkets, public transport and mass gatherings.  Between 30 and 80 percent of people who pass on the Sars-CoV-2 virus do so before they become symptomatic [1,2].  A double layer of cotton in front of the mouth and nose reduces droplet emission by more than 80 percent (95 percent if a waterproof lining is used) [3].  So a home-made face covering will greatly reduce the risk each of us poses to our fellow citizens – and will also give some protection to the wearer.  Importantly, a culture of wearing face coverings in public will convey some important societal messages: we’re taking collective responsibility for stamping out this pandemic (my mask protects you; yours protects me).  This is an unprecedented measure, but we live in unprecedented times.  It will be better than staying in lockdown forever.”

1. Kay J. COVID-19 superspreader events in 28 countries: critical patterns and lessons. Quillette 2020;23rd April

2. Gandhi M, Yokoe DS, Havlir DV. Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19: Mass Medical Soc, 2020.

3. Konda A, Prakash A, Moss GA, et al. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020 doi: 10.1021/acsnano.0c03252

All our previous output on this subject click here

Declared interests

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