A new coronavirus outbreak, which originated in the Chinese city of Wuhan and has spread throughout Asia and globally, has prompted people around the world to buy medical face masks in hopes of preventing infection.
Retailers in the U.S. and across the Internet are running out of antiviral face masks as the number of confirmed cases of the coronavirus (2019-nCoV) now exceeds 9,700 globally. More than 200 people have died from the virus in China, where the majority of the 2019-nCoV cases have been detected. The World Health Organization declared a global health emergency on Thursday as the outbreak continues to spread. As of Friday morning, the United Kingdom and Russia had both confirmed their first cases of the viral infection.
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Local government officials in Wuhan have required that people wear face masks when they go out in public places to prevent the spread of infection. Health experts tell TIME that such a move is probably effective in the city, where a person is more likely to come in contact with someone who is infected than in other parts of the world.
But in the U.S., where just six cases of the coronavirus have so far been detected, wearing face masks will not be that effective, experts say. That’s largely because, according to public health workers, there is no sustained person-to-person transmission of the new coronavirus in the U.S., making face masks not yet necessary.
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“People believe wearing masks will protect them against a novel organism they’re scared about,” says Saskia Popescu, a senior infection prevention epidemiologist at a private healthcare system in Phoenix, Ariz. “I understand the fear, but the U.S. is at a very low risk for this right now.”
Here’s what to know about using face masks in connection with the new coronavirus.
What does the CDC say about using face masks?
The Centers for Disease Control and Prevention (CDC) does not currently recommend that people in the U.S. wear face masks in public to prevent infection. Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases, told reporters during a press call on Thursday that the best preventative measures include washing hands and covering coughs.
The CDC has issued guidelines on two different kinds of face masks — surgical masks and N95 respirators — which are commonly worn by health care professionals and those who are already sick.
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Typical surgical masks usually found at pharmacies (and which were sold out on Amazon and other e-tailers as of Friday) are approved by the U.S. Food and Drug Administration to protect the wearer against large droplets or splashes of bodily and infected fluids from others, according to the CDC.
Wearing surgical masks does not prevent a person from inhaling smaller airborne particles; they are not considered respiratory protection by the CDC. Surgical masks are also loose fitting, and when the wearer inhales, there is potential for particles to leak in or out of the sides.
N95 respirators are recommended for healthcare professionals by the CDC in the event they are treating patients who are infected by the new coronavirus. The N95 masks, which require testing and approval by the CDC, are tight fitting and filter out at least 95% of airborne particles.
Although N95 respirators are sold to the public, health and infectious disease experts caution against non-medical professionals wearing them. N95 masks are supposed to be fit tested to ensure they work correctly, so people who are not trained could put them on the wrong way, negating preventative effects, says Dr. Peter Rabinowitz, a director of the MetaCenter for Pandemic Disease Preparedness and Global Health Security at the University of Washington. He adds that N95 masks are difficult for people to wear effectively for prolonged periods of time.
“They tend to slip and change position. It’s easy for air leaks to develop, even if they’re fitted correctly,” he says.
Can face masks prevent diseases?
Studies on the efficacy of face masks in preventing diseases are inconclusive, largely because they have only been conducted on healthcare professionals in their workplace settings. In general, studies have found that if workers use face masks, the risk of spreading disease as they deal with infected patients is reduced, according to experts.
For members of the public, the effects of using face masks are not well known. But experts say already sick and infected people who can’t avoid going outside — especially those who will be in confined spaces or hospital waiting rooms — should wear masks to avoid spreading germs.
“It’s not foolproof, but it does keep you from coughing out infectious particles with any respiratory virus,” says Dr. Marybeth Sexton, assistant professor in the Division of Infectious Diseases at Emory University School of Medicine.
People who aren’t sick should not rely on masks as a way of preventing respiratory infections, according to Popescu, who notes that surgical masks offer “limited protection” against contracting illness. While face masks can be helpful in stopping the spread of germs in certain situations — like when people are in close quarters on a train or packed into a waiting room — they are unlikely to stem the outbreak of the new coronavirus.
“You’re more likely to contract the coronavirus through continued exposure versus being outside walking about,” Popescu says.
What are more effective preventative measures to avoid coronavirus?
Advice from the CDC and health experts on better preventative measures against viruses like the novel coronavirus or influenza is fairly straightforward and involves basic everyday actions.
To help stop the spread of respiratory infections, it is recommended that people wash their hands often, avoid touching their faces, keep distance from people who are sick and to stay inside if they are sick.
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