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Can wearing masks stop the spread of viruses? Coronavirus: Who needs masks or other protective gear?
(2 months later)
One of the abiding images of any virus outbreak is people in surgical masks. Facemasks, gloves and other protective gear can help stop the spread of coronavirus, in the right circumstances.
Using them to prevent infection is popular in many countries around the world, most notably China during the current coronavirus outbreak where they are also worn to protect against high pollution levels. Some people are also making homemade masks - and Americans are now being advised to use them in public - but are they safe?
Virologists are sceptical about their effectiveness against airborne viruses. Why doesn't everyone wear a mask?
But there is some evidence to suggest the masks can help prevent hand-to-mouth transmissions. The World Health Organization (WHO) currently says only two groups of people should wear protective masks, those who are:
Surgical masks were first introduced into hospitals in the late 18th Century but they did not make the transition into public use until the Spanish flu outbreak in 1919 that went on to kill over 50 million people. Masks are not recommended for the general public because:
Dr David Carrington, of St George's, University of London, told BBC News "routine surgical masks for the public are not an effective protection against viruses or bacteria carried in the air", which was how "most viruses" were transmitted, because they were too loose, had no air filter and left the eyes exposed. Coronavirus is spread by droplets that can spray into the air when those infected talk, cough and sneeze. These can enter the body through the eyes, nose and mouth, either directly or after touching a contaminated object.
But they could help lower the risk of contracting a virus through the "splash" from a sneeze or a cough and provide some protection against hand-to-mouth transmissions. However, experts at the WHO are now exploring whether the general public might benefit from wearing masks. The group will examine research on whether the virus can be projected further than previously thought.
A 2016 study from New South Wales suggested people touched their faces about 23 times an hour. Do homemade face masks work?
Jonathan Ball, professor of molecular virology at the University of Nottingham, said: "In one well controlled study in a hospital setting, the face mask was as good at preventing influenza infection as a purpose-made respirator." Americans are now advised to use clean cloth or fabric to cover their faces whilst in public. Officials say medical masks are in short supply and should be left for healthcare workers.
Respirators, which tend to feature a specialised air filter, are specifically designed to protect against potentially hazardous airborne particles. Only the sick, or those caring for patients of coronavirus, had previously been told to wear masks. But US officials hope the new rules could stop people without symptoms unknowingly spreading coronavirus.
"However, when you move to studies looking at their effectiveness in the general population, the data is less compelling - it's quite a challenge to keep a mask on for prolonged periods of time," Prof Ball added. However, reusable cloth masks are also not recommended and may even increase the chance of infection, say European advisers.
Dr Connor Bamford, of the Wellcome-Wolfson Institute for Experimental Medicine, at Queen's University Belfast, said "implementing simple hygiene measures" was vastly more effective. They say there is a high chance virus particles could go through cloth. Problems with moisture could also mean the cloth retains the virus, they warn.
"Covering your mouth while sneezing, washing your hands, and not putting your hands to your mouth before washing them, could help limit the risk of catching any respiratory virus," he said. The UK is not advising most people to wear either medical or homemade masks. Health Secretary Matt Hancock says the government is following medical and scientific advice on their use.
The NHS says the best way to avoid catching viruses such as flu is to: England's deputy chief medical officer Prof Jonathan Van Tam says he does not believe that healthy people wearing them in the UK would reduce the spread of the disease. "What matters now is social distancing," he says.
Dr Jake Dunning, head of emerging infections and zoonoses at Public Health England, said: "Although there is a perception that the wearing of facemasks may be beneficial, there is in fact very little evidence of widespread benefit from their use outside of these clinical setting." Despite this, there is lots of advice on how to make face masks online, with some sites suggesting the best options.
He said masks had to be worn correctly, changed frequently and got rid of safely if they were to work properly. However, homemade masks are not regulated whereas officially-made ones have to meet safety requirements.
"Research also shows that compliance with these recommended behaviours reduces over time when wearing facemasks for prolonged periods," he added. What do I need to know about the coronavirus?
People would be better to focus on good personal and hand hygiene if they are concerned, Dr Dunning said. What is the best type of mask?
In hospitals, different types of mask offer different grades of protection.
The most protective is an FFP3 or, alternatively, an N95 or an FFP2.
Experts do not recommend the public use these masks. They are for healthcare workers in close contact with coronavirus patients and at highest risk of encountering infected airborne droplets.
Other NHS staff in lower-risk situations can wear a surgical mask, latest guidelines say. That means healthcare workers within one metre of a patient with possible or confirmed Covid-19, and it includes staff working in hospitals, primary care, ambulance trusts, community care settings and care homes.
What else can protect against coronavirus?
Gloves and other protective wear are recommended for NHS staff working in places where they could encounter coronavirus.
Again, staff in the highest-risk scenarios are advised to wear fuller protection, rather than a simple apron, gloves, mask and goggles.
The general public are not advised to wear gloves or any other protective gear.
To protect yourself from coronavirus, the NHS recommends: