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Face masks 'can almost halve number of new coronavirus cases'

The Telegraph logo The Telegraph 10/10/2020 Phoebe Southworth
a woman holding a sign: Woman wearing a face mask - Andrew Milligan /PA © Andrew Milligan/ PA Woman wearing a face mask - Andrew Milligan /PA

Face masks can almost halve the number of new coronavirus cases, a study has claimed.

Covering the face indoors resulted in up to 46 per cent fewer new Covid-19 cases every week in Canada, researchers from Simon Fraser University found.

If masks had been made compulsory in enclosed spaces in the country in early July, the number of new weekly cases could have been reduced by up to 40 per cent (1,100 fewer infections) in mid-August, they claim.

Mask mandates are associated with an average weekly reduction of 25 to 31 per cent in newly diagnosed Covid-19 cases in the first few weeks after they are introduced, the research also found.


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Dr Julian Tang, a consultant virologist at the Leicester Royal Infirmary, said the study adds to a growing body of evidence that masks may be effective at slowing the spread of coronavirus.

He said previous laboratory and observational studies on the effectiveness of masks suggest that the reduction in cases could be even greater than this study reports.

"The authors use a modelling approach to tease out the protective effects of masking from other interventions and conclude that wearing a mask may reduce the risk of infection by about 30 per cent," he said.

"This is lower than the above estimated benefits obtained from laboratory studies, but is still a useful and significant benefit.”

The study, which is yet to be peer reviewed, analysed the impact of mask mandates that were implemented across Ontario's 34 Public Health Units (PHUs) over the course of two months.

Researchers compared the results of PHUs that adopted mask mandates earlier to those that adopted mandates later.

Gallery: Coronavirus outbreak around the world (Photo Services)

Mandates for mask wearing increased self-reported mask usage in Canada by 30 percentage points, according to a survey conducted as part of the study - suggesting a big impact on citizen behaviour.

The findings come as the British Medical Association calls for masks be made compulsory in outdoor spaces in the UK where a two-metre distance cannot be maintained, as well as in offices and other working environments.

Chairman of the doctors' trade union body, Dr Chaand Nagpaul, said: "We are having to swallow a very bitter pill of the infection continuing to spread at a perilous rate. Stronger measures brought in now could be a far sweeter pill in the long run for far more people."

A recent study on face shields, which have been proposed as an alternative to face masks, found they block just two per cent of cough droplets.

"One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking," the study, yet to be peer reviewed, concluded.

Stay alert to stop coronavirus spreading - here is the latest government guidance. If you think you have the virus, don't go to the GP or hospital, stay indoors and get advice online. Only call NHS 111 if you cannot cope with your symptoms at home; your condition gets worse; or your symptoms do not get better after seven days. In parts of Wales where 111 isn't available, call NHS Direct on 0845 46 47. In Scotland anyone with symptoms is advised to self-isolate for seven days. In Northern Ireland, call your GP.


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