Masks and COVID-19: When, how and why you'd wear them
Why do so many Asians wear masks? Are N95 or medical masks better? Should everyone wear one?
Public health officials in North America discourage healthy people from wearing masks, saying there's no evidence they provide effective protection against the spread of the coronavirus, which causes COVID-19. But officials in Asia encourage it. And health workers here say they need masks for protection and are struggling with shortages.
Here's a closer look at what public health officials and the research says about who should wear a mask, how to wear one properly and what kind of protection it offers.
What are the different kinds of masks, and what protection do they offer?
There are three main types of masks that are available:
- N95: These are tight-fitting masks that are designed to seal around the nose and mouth and screen out 95 per cent of small airborne particles. They're likely to prevent transmission of aerosolized virus — those suspended as a mist in the air. Because of that, they're used by health-care workers in specific medical procedures that generate aerosols, such as inserting a breathing tube or bronchoscopy (imaging someone's lungs and air passages), said Dr. Mark Loeb, a professor of pathology and clinical epidemiology at McMaster University in Hamilton.
- Surgical or medical masks: These are looser fitting, more flexible disposable masks that are considered effective barriers against large droplets released by talking, coughing or sneezing — the main way COVID-19 is likely transmitted.
- Reusable cloth masks: You may have seen many volunteers sewing these for distribution, and some hospitals in the United States were even asking for them as a last resort due to shortages of other kinds of masks. However, their effectiveness hasn't been studied much and would depend on the type of fabric, said Dr. Michael Gardam, an infectious disease specialist and chief of staff for Humber River Hospital in Toronto. "They do tend to be quite porous," he added. At least one Toronto hospital has requested such masks for people who don't work in health care, such as hospital visitors or recently discharged patients.
Which mask is recommended for health-care workers?
For everyday medical care, recommendations vary, said Loeb. For example, the U.S. national Centers for Disease Control and Prevention recommends the use of N95 masks, but the Public Health Agency of Canada recommends a medical mask, and Ontario previously recommended N95 and is now recommending medical masks.
However, Loeb said N95 masks are definitely needed for special medical procedures that generate aerosols.
How effectively do masks protect health-care workers?
Consistent use of either N95 or surgical masks reduced infection with SARS, another coronavirus, by roughly 80 per cent among health-care workers, said Loeb, based on both his own research and a study by another research group. Both the SARS studies and a more recent study on a variety of respiratory illnesses, including coronaviruses, didn't find a big difference in protection between the two kinds of masks for regular medical procedures. Loeb is currently setting up a randomized control trial to confirm whether there is a difference for COVID-19.
However, Gardam noted that masks are never used alone as personal protective equipment by health-care workers — they go with face shields, gowns and gloves.
When are masks recommended for members of the public?
N95 masks are not generally recommended for the public in North America for protection against disease. But the World Health Organization (WHO) recommends wearing a medical mask at home, if you:
Have symptoms, like coughing or sneezing, as it can reduce contagious droplets from being sprayed around you.
Are caring for someone with a suspected COVID-19 infection.
However, typically, public health officials in North America and Europe say healthy people shouldn't wear masks in public. And right now, most people with respiratory symptoms shouldn't be leaving their homes.
What's the proper way to use a mask?
Before putting on a mask, clean your hands with soap and water or alcohol-based hand sanitizer.
Cover your mouth and nose with the mask and make sure there are no gaps between your face and the mask.
Avoid touching the mask while using it and clean your hands if you do.
Replace the mask with a new one as soon as it's damp and don't reuse single-use masks.
Remove it from behind, discard immediately into a closed bin and then clean your hands with soap and water or alcohol-based hand sanitizer.
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How effective are masks at protecting you against respiratory infections such as COVID-19?
We don't know specifically for COVID-19, but studies of families where someone has the flu show mask usage is not that effective at preventing transmission, said Gardam. "It's not at all the dramatic reduction that you would want."
That's probably because the masks have to be used properly and consistently all the time, he said.
On the other hand, "it's not going to hurt. It might help," he said.
But he noted frequent handwashing and keeping at least two metres away from other people are probably more effective and still need to be used in conjunction with a mask.
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Why shouldn't healthy people wear masks while in public?
Because they don't need them, and there's a shortage, said Loeb.
"People are walking down the street with these masks," he said, "And I think that's a waste."
Ordinary people should be social distancing so they're never in a position where they might be exposed to a cough or sneeze from someone with COVID-19, he said.
Meanwhile, health-care professionals, who certainly will be exposed, are running out: "There's a very limited supply that's getting more limited."
Researchers and public health officials say improper use of face masks, such as not changing disposable masks or not handwashing could potentially increase risk of disease transmission.
There also is limited evidence that healthy people wearing masks reduces the community spread of diseases, like COVID-19, as public health officials have been saying, but some acknowledge that's partly because studies haven't been done.
Are there exceptions where healthy people should wear masks in public?
Maybe. In a recent article in the Lancet, researchers led by Elaine Shuo Feng, a postdoctoral researcher with the University of Oxford Vaccine Group, suggested it would be "rational" to recommend wearing face masks in public to:
- Healthy people in quarantine (or self-isolation) if they need to leave home for any reason.
- Vulnerable people, such as older adults, and those with underlying medical conditions.
Gardam said while wearing a mask makes "zero sense" while walking down the street, there is a logic to using one if you're forced to be in an enclosed space, such as public transit or a crowded grocery store (although many grocery stores are now limiting the number of customers inside).
Why is there so much more mask-wearing in Asia and among Asian people?
In Asian countries, there are many circumstances where mask-wearing is recommended or required, according to Feng's paper, which looked into the variation. For example, in China, as part of strategies to reduce the transmission of COVID-19, some provinces and municipalities make face masks compulsory in public areas, and it's recommended while shopping or in gatherings of children and students. Hong Kong specifically recommends masks when taking in public transit or staying in crowded places.
The researchers also said that for cultural reasons, masks are considered a hygienic practice even for healthy people in Asia, while in North America it's considered something only sick people do.
Are there possible advantages to everyone wearing masks?
Feng's study suggested two possible advantages:
- It might reduce community transmission, since there's evidence COVID-19 can be transmitted before symptoms begin.
- It could reduce discrimination and racial aggression against people who wear masks.
For now, what's the take-home message on masks?
"If you're not around people, you don't need a mask," Gardam said. "Relying on masks as a safety net is questionable."
Loeb said the masks should be left for the health-care workers who need them. For everyone else: "Wash your hands and listen to the social distancing message. That's it."