Keep wearing masks to slow spread of Covid, scientists warn Britons | Coronavirus | The Guardian
Scientists have strongly endorsed the continued wearing of masks in enclosed public spaces over summer. As Covid-19 cases continue to spiral, face coverings offer people the most robust way of limiting the spread of the disease in cafes, theatres and restaurants, they said last week.
Rates of new Covid-19 cases topped 50,000 a day last week, leading scientists and health experts to warn that the country could be forced into a lockdown later this year as rising numbers of infections look likely to continue until autumn. In these circumstances, they said, wearing of masks should be continued despite the government’s refusal to make such a move official.
“If you don’t wear masks, the virus will spread further. It is as simple as that,” said Julian Tang, a clinical virologist at Leicester University.
Tang said masks clearly limit the spread of viral particles from an infected person and also cut a wearer’s chance of picking up an infection from someone else. “Masks work both ways,” he told the Observer.
“If you assume that a mask at least halves transmission, that means that for every 1,000 virus particles an infected person breathes out, only 500 will leave your mask. Then, when those particles reach someone else, similarly their masks will ensure at least a twofold reduction in the number of viruses reaching their mouths or noses. In other words, of the 1,000 virus particles an infected person has breathed out, only 250 or so will reach another person. That should reduce infection rates, and that is why masks are important.”
This point was backed by Paul Hunter, professor of medicine at the University of East Anglia. “Most studies are observational and prone to all sorts of biases, but taken together there is a consistent finding towards face coverings having benefit both in protecting others if the wearer is infected and also to protect the wearer from others,” he told the Observer. “Estimates vary but they probably reduce transmission somewhere between 10 and 25%.”
However, it is crucial that there is a high uptake of mask wearing, said Paul Edelstein, emeritus professor of pathology at the University of Pennsylvania. “Good protection requires that most people wear masks; wearing a standard cloth or medical mask in a room containing unmasked infected people probably does not provide great protection; basically, mask-wearing must be by most persons in order to reduce infection rates,” he added.
Edelstein said experiments showed that multilayer cloth masks were likely to provide better control and protection than single-layer, loosely woven masks. “There is also relatively little transmission outdoors when there is good ventilation, so masks are generally superfluous under those circumstances. However, being in a jostling, shouting crowd outdoors is probably a greater risk than when you are walking on a quiet street.”
Catherine Noakes, professor of Environmental Engineering for Buildings at Leeds University, said that people should realise they would not be wearing masks for ever.
“However, at times of very high virus prevalence, as we are now experiencing, they start to become really important. The more that other protective measures are taken away, the more we have to ensure the measures we’ve got left are working, and encouraging people to wear good quality masks is one of the most important of these.”
She added: “If you are in a shop or a restaurant or a train where there are a lot of people, there’s quite a high probability that one of them is infected. However, the more people who wear masks in these settings, then the greater will be the reduction in virus transmission and infections.”
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