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There is enough evidence to show masks offer at least some protection against catching and spreading Covid, experts said today amid fears that a culture war could break out over coverings after July 19.
Throughout the pandemic there has been fierce scientific debate about how well the guards work at reducing transmission, despite nearly every country in the world mandating or encouraging their use.
Wearing a mask will become personal choice instead of a legal requirement when England finally comes out of lockdown later this month, in a move that sparked a fresh row about their effectiveness.
Experts told MailOnline today they were confident there is ‘some’ benefit to wearing masks to prevent Covid from spreading — but they admitted to what degree remains unknown because there is a lack of quality evidence.
Cambridge University’s Dr Raghib Ali, a clinical epidemiologist, added the vaccines are doing such a good job at reducing transmission that there is now little need for masks to be worn everywhere.
But he said they could still be beneficial in hospitals, care homes and in crowded and poorly ventilated areas like the Tube, adding that a high-grade FFP3 mask would be the best option over a surgical or cloth mask.
Lab tests and observational studies have shown masks can block infected people from exhaling up to 80 per cent of the virus into the air and also protect wearers from inhaling up to 50 per cent of the particles.
But real-world studies, which involve more scientific rigour, have produced mixed results, with some showing a huge impact on infection rates and others showing virtually none.
Government scientific adviser Professor Robert Dingwall, a sociologist at the University of Nottingham, said the quality of the evidence in both directions is ‘so weak’.
‘It’s really been the working from home and shutting down society that has reduced transmission, face masks and interpersonal distances will have only played a small role,’ he told MailOnline.
A lab study by Duke University in North Carolina showed that a variety of different face masks reduced the amount of viral droplets expelled into the air. The N95 and surgical masks were found to be much better than various cotton and other cloth coverings but every type was better than none. In the study, a mask wearer repeated the sentence ‘Stay healthy, people’ five times, after which and researchers used a thermal camera and thermal camera to monitor the amount of droplets released
A similar study by the Centers for Disease Control and Prevention (CDC) in the US looked at how efficient each type of covering was at blocking different sized droplets (shown along the bottom). Again, the high-grade N95 mask was shown to collect 100 per cent of droplets except the finest. Surgical masks (orange) and double-layered cloth masks (in lighter blue) performed second best. Gaiter 1-layer represents a single cloth mask
A laboratory experiment by the University of Edinburgh showed that even cotton masks (left) and face shields (right) reduced the distance Covid particles travel when exhaled by 90 per cent. Although handmade masks (left) stop breath flowing forwards, exhaled air leaks elsewhere, which meant that the risk of passing Covid to someone nearby was still higher than with a tight-fitting industrial mask. Full-face shields generated a strong downward jet (right)
A randomised study known as the ‘Danmask’ trial, published by scientists at Copenhagen University over winter, found no statistical evidence that they offer any protection whatsoever. Experts recruited 6,000 volunteers in the spring — before masks were mandatory there — and split the them into two groups, with half wearing masks in public and half not. Results showed that, after one month, 1.8 per cent of the people wearing masks had been infected with the virus. By comparison, 2.1 per cent of the people in the unmasked group had tested positive for Covid
Vaccines have been proven to reduce Covid transmission by at least 60 per cent after two doses, but studying the effect of masks is more difficult because there are more variables – including how often a person wears the mask, what type they use and if it fits properly.
A retrospective US trial in Missouri last May looked at two hairdressers who had Covid and interacted with nearly 140 clients over the space of a week. Of the clients who wore masks during their appointment, none caught the virus.
Another real-world study looked at 124 households with a confirmed case of Covid in Beijing last February. It found that, when masks were worn by everyone in communal rooms in the home, transmission was reduced by 79 per cent.
A report published in the Lancet last June found the risk of catching Covid was as low as 3 per cent if people wore masks and properly social distanced from others. The findings were based on 172 studies in 16 countries.
In a Thai study published in November, researchers found that of 1,000 patients contacted through test and trace systems, those who reported always wearing a mask in public were 70 per cent less likely to become infected than those who didn’t.
A laboratory experiment by the University of Edinburgh showed that even the most flimsy face coverings reduce the distance Covid particles travel when exhaled by 90 per cent. Despite the findings, scientists still cannot say for certain how effective masks really are.
Professor Dingwall, who sits on the Joint Committee on Vaccination and Immunisation (JCVI) which advises No10 on the Covid jab rollout, told MailOnline: ‘The problem is we don’t have many randomised studies.
‘Instead we’ve got observational studies, modelling studies and laboratory studies where findings can be cherry-picked. The randomised trials we do have don’t show much benefit [to wearing masks].’
A randomised study known as the ‘Danmask’ trial, published by scientists at Copenhagen University over winter, found no statistical evidence that they offer any protection whatsoever.
Experts recruited 6,000 volunteers in the spring — before masks were mandatory there — and split the them into two groups, with half wearing masks in public and half not.
Results showed that, after one month, 1.8 per cent of the people wearing masks had been infected with the virus. By comparison, 2.1 per cent of the people in the unmasked group had tested positive for Covid. The difference between the two groups was not found to be statistically significant.
However, the findings from the Danmask study came under scrutiny, with critics pointing out that less than half of participants actually wore masks when they were supposed to.
It also only looked at the benefit of masks on protecting the wearer. Masks are thought to be much better at preventing infected people from passing the disease onto others, which the trial did not look at.
The Copenhagen researchers noted this, writing: ‘The findings, however, should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing SARS-CoV-2 infections, because the trial did not test the role of masks in source control of SARS-CoV-2 infection.’
Two other real-world studies – in Guinea-Bissau and India – found no evidence that masks significantly reduce Covid transmission.
Oxford University’s Professor Carl Heneghan and Dr Tom Jefferson, from the prestigious Centre for Evidence-Based Medicine, said following the Danmask study: ‘Now we have properly rigorous scientific research we can rely on, the evidence shows wearing masks in the community does not significantly reduce the rates of infection.’
In its recommendations, the World Health Organization concluded that the use of a mask alone ‘is not sufficient to provide an adequate level of protection against COVID-19.’
However, Dr Ali told MailOnline today that it was ‘common sense’ that wearing some form of mouth guard will give at least partial protection against catching or spreading any virus.
He added: ‘Looking at the totality of evidence over the past year, my view is there’s enough evidence to say that wearing masks both protects the person wearing it and stops them passing it on.
‘But how big that protection is is uncertain. I’m confident there’s some benefit, if you look at hospitals before and after they introduced face masks, even ordinary surgical ones, infection rates in hospitals came down.
Dr Ali said that the best protection against catching or passing on the virus was to get vaccinated.
Sadiq Khan has suggested that face masks could still be required on the Tube even if the national rules change
‘My advice to people who are worried about masks not being mandatory would be to get vaccinated, it’s the most important thing,’ he added. ‘f they’re still worried, or if they are vulnerable or can’t be vaccinated, then buy a FFP3 mask.’
The Government should have kept masks and social distancing mandatory on public transport, Dr Ali said, because ‘now we’re going to have weird situation where some people are and some aren’t’ wearing masks and distancing’.
Professor Dingwall told MailOnline that there was now a danger of a culture war erupting over face masks when Britain emerges from lockdown.
‘In the absence of a clear scientific case for continuing to wear masks, the issue is being framed as a moral or ethical case.
‘There is an attempt to say that unless you continue wearing mask, you don’t care about other people’s welfare.’
At a Downing Street press conference on Monday evening, Prime Minister Boris Johnson declared that mask laws would be axed – but sowed confusion after admitting that people would still be encouraged to wear coverings in ‘enclosed and crowded places’.
He confirmed that he would continue to wear a mask in certain scenarios out of politeness. Mr Johnson was echoed by Chief Medical Officer Chris Whitty, who said he would cover his mouth and nose when in crowded spaces, when asked to by a competent authority, or if he felt that not wearing a mask would make another person uncomfortable.
Sir Patrick Vallance, the Chief Scientific Adviser, added: ‘I’m exactly the same in terms of mask-wearing.’
Experts appear divided on whether people in England should be asked to continue to wear face masks after July 19, with Dr Laurence Aitchison, from the department of computer science at the University of Bristol, saying: ‘Our research has shown mask-wearing reduces the spread of Covid-19 by around 25 per cent if everyone wears them.’
Paul Hunter, professor in medicine at the University of East Anglia, said he thought lifting face mask restrictions was fine, though people who are vulnerable may wish to take extra care as he warned Covid ‘will never go away’.
But masks are controversial among anti-lockdown Tory backbenchers. Ex-minister Steve Baker, the deputy chairman of the Covid Recovery Group of MPs, told the Telegraph newspaper ‘how easily we have forgotten that at the beginning of this crisis, the scientific advice was that the public shouldn’t wear masks’.
Sir Paul Nurse, director of the Francis Crick Institute, said today that it made ‘no sense not to insist on the wearing of masks’.
His comments came as Business Secretary Kwasi Kwarteng said he will ‘probably’ wear a mask on the London Underground after the legal requirement ends.
Sir Paul told BBC Radio 4’s Today programme: ‘I think it’s not unreasonable for the Government to open the country up more, given the successful vaccine rollout. But it’s not sensible to open up so much so fast when the level of infections is rising so quickly.
‘This decision is informed by science but it’s a political decision. And some factors are important, like the economy, but some of this could be achieved by keeping some of the checks in place.
‘It makes no sense not to insist on the wearing of masks. We need sensible, well thought-out, good plans.
‘Of course we have to make the most of the summer but it doesn’t mean we have to open the door wide open.’
And Mr Kwarteng told Sky News: ‘Personally, I use the Tube a lot in London, and I would probably wear a mask in that context, on the Tube, on public transport.
‘That’s a personal view, it’s not something I would mandate, or necessarily dictate to other people.’
Meanwhile, Dr Katherine Henderson, president of the Royal College of Emergency Medicine, said face masks may still be needed in A&E departments to ‘keep people safe’.
‘So, we haven’t seen what the plans are for hospitals, but the likelihood is that we will want to make it as safe as possible for everybody,’ she told Times Radio.
‘And the only way to do that will be to maintain the hand hygiene, the social distancing and mask-wearing within a hospital.
‘A&E departments are often quite crowded environments and that’s one of our worries – so, as people come in, we may need mask-wearing to help keep other people safe because you might be an asymptomatic carrier and come with a cut finger, but you might be near somebody who’s immunosuppressed with a kidney transplant.’
Professor Laurence Lovat, clinical director at the Weiss Centre at UCL, questioned whether it is ‘wise’ to make face masks optional.
He told Sky News: ‘There is no doubt that face masks have an enormous impact on the transmission of droplets – these tiny aerosols that sort of float around in the air.
‘And one thing we really don’t want to be doing is to have a major spike of patients coming into hospitals again just as hospitals are starting to settle down and get back to routine work.
‘And face masks are a really simple way to prevent people from transmitting disease to others.’
Meanwhile, Professor Sir John Bell said there is no need to ‘wobble’ on plans to ease coronavirus restrictions, and suggested that immunity from vaccinations could be increasing over time.
The regius professor of medicine at Oxford University said he is encouraged by evidence that vaccines are ‘holding their own’ by reducing the likelihood of hospital admission and death to ‘very small indeed’ after both doses.
‘That’s what the Government is counting on and I see no reason to wobble on that,’ he told the Today programme.
‘The second thing is, our immune responses seem to get better over time. After you’ve had two vaccines, when you pop back up six months later, your immune system has developed the response to the virus to an even more mature state.
‘So, I think, not only have we got good immunity but that immunity may well improve over time. As you know, I’m a sort of glass half-full guy and I’m sort of three-quarters full at the moment.’
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