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As the number of confirmed cases of COVID-19 continues to rise sharply in the U.S., the Centers for Disease Control and Prevention is now recommending that people wear face coverings when out in public.
The new guidance to wear a non-medical "basic cloth or fabric mask" is voluntary, President Trump said Friday. But it represents a shift for the CDC, which previously said that healthy people who aren’t caring for someone who is sick don’t need to wear face masks to protect themselves from the novel coronavirus. The World Health Organization still says that most healthy people don't need masks.
The announcement comes after a growing number of health experts have in recent days began suggesting that we should all be wearing masks of some kind. In fact, several large health departments, including those of Los Angeles and New York City, already advised all residents to wear face covering when out in public.
Federal officials stress that the use of masks should be in addition to all the other measures currently recommended for COVID-19 prevention, including social distancing.
Deborah Birx, M.D., coronavirus response coordinator for the White House coronavirus task force, said Thursday night that people wearing a face covering should not be lulled into a false sense of security, and must keep up with diligent handwashing, avoid face touching, and stay at least 6 feet away from those they do not live with.
Most people should not use medical masks—either loose-fitting surgical masks or the more snug N95s—because these should be reserved for healthcare professionals who need them to protect against COVID-19 while in close contact with patients, officials say.
The two city health departments advised using common household items like scarves, bandanas, or other cloth. Trump and Surgeon General Jerome Adams, M.D., M.P.H., recommended simple masks that could be made at home or purchased online. These reusable, washable items are constructed from materials like cloth scraps, and won't further stress the supply of medical masks.
Public health experts have also emphasized that the potential benefit of wearing a face covering is not to protect yourself, but to safeguard others around you, in case you are infected but don’t know it yet.
That's because a significant share of people with COVID019—perhaps as many as a quarter, by some estimates—show no symptoms. But they may still be contagious.
“If you put a mask on someone who is ill, they are less likely to spread the virus to others,” says Tom Frieden, M.D., a former director of the CDC. “That includes people who don’t have symptoms. We know people who don’t have symptoms can spread the virus."
Here’s what you need to know now about mask use amid the COVID-19 pandemic.
What Protection Might Masks Provide?
Some experts have said that there’s little reason for the average person to wear a mask. “In the research that’s been done, we don’t see any benefit at the community level for wearing the mask,” said Amanda McClelland, M.P.H., a senior vice president at Vital Strategies, a public health organization that focuses on global health threats.
Still, some evidence suggests that masks may be useful for this group, although the extent of any potential benefit is unclear. A 2011 Cochrane review of 67 studies found that mask use, hand-washing, and isolating sick people, especially when used together, can be effective in containing viral epidemics.
And studies of dorms and other high-density settings like households do show some efficacy for masks, according to Raina MacIntyre, Ph.D., professor of global biosecurity at the University of New South Wales Sydney in Australia. For instance, a 2010 study found that the combination of mask use, providing alcohol-based hand sanitizer, and education about hand and cough hygiene reduced the prevalence of flulike illness inside a college dorm more than only hand and cough hygiene education. “If they work in high-transmission settings, they should also work in low-intensity settings,” out in the community, MacIntyre said.
In the case of COVID-19, having everyone wear masks—as the new CDC guidance recommends—may reduce the spread of the virus by people who are infected but not experiencing symptoms, said Donald K. Milton, M.D., Dr.P.H., a professor of environmental and occupational health at the University of Maryland in College Park.
“The argument is that since anyone can be infected without knowing it and spread the infection, that everyone should wear masks,” Milton said. “In the U.S., where we are not prepared to test rapidly and aggressively trace and quarantine all contacts, surgical masks could be helpful.”
Who Should Wear a Medical Mask?
Healthcare workers should use masks to protect themselves when taking care of patients suspected of having COVID-19, according to the CDC. People with symptoms that might signal COVID-19—such as a fever, a cough, and shortness of breath—should also wear a mask when they are around others, to limit the spread of infection, the CDC says.
If you’re caring for someone who may have COVID-19, you should also wear a mask, according to the CDC and the WHO. The reason: So far, the novel coronavirus is thought to spread mainly between people who have close contact—meaning within 6 feet—with each other. That’s how far droplets of bodily fluid that might contain infectious virus are probably able to travel through a cough or sneeze, the CDC says.
But in some instances, especially during certain hospital procedures, the virus may be able to float in smaller particles in the air, a process known as aerosol transmission.
For the rest of us, medical masks are not necessary, the CDC reiterates in the new guidance. The supply of surgical masks and N95s, which are both meant to be used by healthcare workers for one patient and then thrown away, continues to be severely strained.
In fact, stocks are so low that the CDC has issued guidance on extending the life of protective gear, such as using one mask to care for multiple patients.
“I don’t think we are at the point where there is strong evidence that mask wearing by the general public will be helpful, and I don’t think it is prudent to advocate for this when there are real concerns for healthcare workers,” said Amesh Adalja, M.D., an infectious-disease physician and senior scholar at the Johns Hopkins University Center for Health Security in Baltimore. MacIntyre, too, said that surgical masks and N95 respirators need to be saved for healthcare workers right now.
But some countries have advised broader mask use. In China, for example, authorities advise that people wear disposable medical masks in public places and on public transportation; in Hong Kong authorities have recommended wearing these when taking public transportation and in crowded areas.
Such recommendations “could be considered” more globally if we’re able to dramatically increase the available mask supply, according to an article published in The Lancet Respiratory Medicine journal in March.
While evidence that masks used outside of healthcare prevent respiratory infections from spreading is still scant, the authors write, people at higher risk for the disease may want to consider wearing a surgical mask when in high-risk areas, where there are crowds of potentially infected people.
It may also be rational to recommend that anyone in quarantine who needs to go outside wears a mask “to prevent potential asymptomatic or presymptomatic transmission,” they write.
What About Homemade Masks?
When it comes to the evidence on the kinds of face coverings the CDC is now recommending, effectiveness is mixed. A study published in The BMJ in 2015 found that healthcare workers using cloth masks were more likely to be infected with respiratory diseases than those who used disposable surgical masks, even when workers washed them at the end of each of their shifts.
Two laboratory studies, one published in 2013 in the journal Disaster Medicine and Public Health Preparedness by scientists with Public Health England and another published in Plos One in 2008 by scientists in the Netherlands, have demonstrated that masks made of household materials, such as T-shirt scraps, tea cloths, or vacuum bags, aren’t as effective at blocking particles of virus in droplets and aerosols as surgical masks. Still, they did provide some protection—especially, according to the Public Health England study, those made of vacuum bags, tea towels, and blended cotton fabric.
Even manufactured surgical masks and N95 respirator use can be tricky for people who aren’t trained and used to them. In fact, healthcare workers must take an annual test (PDF) to prove that they can properly fit and seal an N95 mask.
While some experts say wearing a homemade or purchased mask may help you remember not to touch your face, others note that they can be uncomfortable, leading wearers to adjust them often. Or you might take a mask off to eat or drink, then put it back on afterward. That defeats the purpose, said McClelland at Vital Strategies. “People contaminate themselves more by touching the mask and taking it on and off their face.”
As Birx noted, mask wearers must still continue other safety measures, including social distancing. “Because homemade ones are not even as effective at filtering out virus as commercial surgical masks, which are not great, people should be aware that these are not protective and should not do anything you would not do without one of them on,” Milton said.
How to Wear a Mask Properly
If you live in Los Angeles, New York City, Newark, N.J., or another area that has directed people to wear face coverings in public, look up the specific guidelines for whatever city you’re in. New York City’s guidelines are fairly extensive.
For instance, New York says that people should use a face covering when out in public and near people, but that they don't have to wear one while doing solo exercise like biking or running outdoors, as long as they're able to stay more than 6 feet away from others.
The surgeon general said that people wash their hands before donning a mask, and avoid touching their faces while wearing one. New York City recommends people hand or machine wash cloth face coverings once a day, and wear them again only once they’re completely dry. You may want to rotate using a few different face coverings.
You’ll also need to wash your hands after you take the mask off, and store it somewhere where it won’t be touched by anyone in your house, or where it will contaminate other surfaces.
So far, there are no national instructions on the right way to make a mask or the best materials to use. However, some mask “recipes” are available online, such as this one from a Wisconsin hospital asking for donations of homemade masks as a supplement to their supplies.
If you wear a disposable mask, such as a surgical mask, while ill or caring for someone else, it’s essential to follow proper safety steps. Wash your hands before putting the mask on, then try not to touch it. If you do, wash your hands again. Discard the mask as soon as it’s damp. To remove it, handle the elastic around your ears, not the front of the mask, throw it away immediately—either in a closed plastic bag or a bin with a lid—and wash your hands again. Don’t reuse the mask.
Best Steps for Prevention
Until we get more clarity from federal health officials about mask use, everyone should take the following steps to help prevent the spread of the coronavirus and other infections.
First: Practice social distancing. Stay home as much as possible, and when you do have to go out, avoid crowds and keep 6 feet between yourself and others.
“Impeccable hand hygiene is [also] key,” said Isaac Bogoch, M.D., an epidemiologist and associate professor of infectious disease in the department of medicine at the University of Toronto. That’s to protect you from exposure to droplets of fluid from coughs or sneezes that contain the virus.
Wash hands frequently, scrubbing thoroughly for the recommended 20 seconds.
Use hand sanitizer when you can’t get to a sink—after touching a handrail or door handle, on public transit, or using a shared keyboard at the library, for example.
Abstaining from touching your face is also important because that’s how germs get transferred from your hands to your mouth or nose, and enter your body. “It’s easy to say but hard to do,” Bogoch said, but now is the time to make this a habit.
And of course, cover any coughs or sneezes with a tissue, and if you can’t, sneeze or cough into the crook of your elbow.
Editor's Note: This story was originally published on March 2. It has been updated to include additional research and expert advice.
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