A group led by Canadian doctors and scientists is calling on health authorities to make face masks mandatory in all indoor spaces outside the home.

While the Public Health Agency of Canada recommends the use of masks and face coverings when physical distancing is not possible, Amy Tan, one of the organizers of Masks4Canada, said making them mandatory would send a clear message that they can help.

“By clearly articulating the expectation is there, it takes the wishy-washiness away from it,” said Dr. Tan, a family physician and an associate professor at the University of Calgary. “We think that mandating is not about harsh penalties or punishment. It’s really to say we need to do this for our economy, for our community, to keep us safe.”

Canadian public-health officials have shifted their stance since the early days of the pandemic, when they advised that face masks were unnecessary for healthy individuals – and, worse, could contribute to the spread of germs if people often touch their faces while wearing them. In April, the federal public-health agency began recommending their use, as Canada’s Chief Public Health Officer Theresa Tam noted the scientific evidence had evolved.

But deciding whether to require them is a complex matter. In spite of recent public pressure, the federal public-health agency, provincial health bodies and other authorities have not gone so far as to call for them to be mandatory. Among the oft-cited reasons for not requiring masks is the difficulty of enforcing such a rule.

Alberta Premier Jason Kenney, for instance, told reporters this month he wanted to avoid having police and bylaw officers ticket or arrest people for not wearing masks or face coverings. Instead, his province very strongly recommends them and is distributing masks without charge at drive-thru restaurants.

And while new research suggests face masks may help reduce the spread of COVID-19, experts note the evidence is by no means conclusive.

But Dr. Tan said Canadians don’t have the luxury of time to wait, and that the best evidence available supports the case for non-medical cloth masks. A recent Leger poll showed only about 55 per cent of Canadians wear masks to grocery stores, she said, noting that merely recommending them is not enough.

Her group is not necessarily calling for a blanket requirement across the country, but rather believes masks should be made mandatory by authorities in areas with high population density and where there’s community spread of COVID-19.

In providing his rationale for not making masks mandatory via Twitter, Mustafa Hirji, acting medical officer of health for Ontario’s Niagara region, said without enforcement an order would effectively just be a recommendation. He also cited a systematic review and meta-analysis in The Lancet that found only “low certainty” that masks were effective.

Derek Chu, a co-author of that review and clinician scientist at McMaster University in Hamilton, explained the studies he and his team examined showed masks probably provide protection against the coronavirus. But he also offered several caveats. The studies they looked at were observational studies, not randomized controlled trials, which are considered the gold standard in research. Moreover, most were conducted in a health care setting or among people taking care of sick individuals, not in general public situations, he said.

As a result, some people may argue the results of these studies cannot be applied to grocery stores or shopping malls, while others may argue that if masks are shown to work in high-risk health care settings, they should also work for low-risk public scenarios, Dr. Chu said.

“Many people can make rationales for either side,” he said.

Policy makers face a number of other considerations, he added, including how to make sure people have equitable access to masks, how to address those who can’t wear them, and precisely when and where people should wear them. In addition, mask wearing is only one among several measures to curtail the pandemic, including hand hygiene, testing, self-isolating and physical distancing, he said.

The extent to which a mask reduces one’s risk of infection also depends, in part, on the context, Dr. Chu said.

Catherine Clase, an associate professor of medicine at McMaster and nephrologist at St. Joseph’s Healthcare Hamilton, put it this way: She predicted masks may be most effective in high-risk situations, like at meat-packing facilities, where people are working closely together and shouting or speaking loudly. By contrast, if you’re walking outside, wearing a mask would probably not make much difference, she said.

“Rather than wondering about whether the government is going to make mask wearing mandatory, we might want to try and break it down and think about different risk situations,” said Dr. Clase, who co-authored an opinion piece last month in the Annals of Internal Medicine on the use of cloth masks to prevent COVID-19 transmission.

She and her team found that studies showed cloth masks made and worn in the 1960s and 1970s could filter more than 90 per cent of particles, and close to 90 per cent of aerosols. Nevertheless, she explained, these studies only provide evidence of the efficiency of masks – that is, the proportion of particles masks can block – but not their effectiveness in reducing the number of people who get infected. Showing effectiveness typically requires large, randomized controlled trials.

“We don’t have those trials,” she said. “That’s why it’s still not an easy public-health decision.”

At Ontario’s Wellington-Dufferin-Guelph Health Unit, one of the few jurisdictions in Canada to make face coverings mandatory at commercial establishments, Medical Officer of Health Nicola Mercer said she instituted the measure to provide greater protection at a population level.

“If most people are doing it, then the impact is much greater than if a few people are doing it,” she said, noting, “That is the same concept for vaccines.”

Highlights from a live Q&A with The Globe’s health columnist André Picard, where he answers questions on masks, protesting in the age of COVID-19, long term care homes, coronavirus antibodies and adapting to a future where COVID-19 remains in our society.

WENCY LEUNG
HEALTH REPORTER
The Globe and Mail, June 30, 2020