The battle against airborne COVID has shifted. Why your mask is the last layer of defence

Whether it's the moviegoer who ditches their mask at the start of the show to eat popcorn and never puts it on again, or the commuter on the subway who sports theirs just below the nose, mask use in Ontario seems to be slipping, literally.

But with COVID-19 cases ticking up again with the cold weather, a reopened economy, and vaccination rates plateauing, Canada's chief public health officer is urging people to double down on masking as a tool to help stop airborne transmission.

In a series of tweets over the weekend, Dr. Theresa Tam stressed that the virus can linger in the air we breathe, much like second-hand smoke, and a well-fitting mask is vital to protect yourself when spending time in indoor public spaces, particularly in the absence of good ventilation.

There has been a paradigm shift in the thinking behind mask use, to the current emphasis on protecting oneself as opposed to the initial consideration of keeping others safe from what we might be exhaling, said Colin Furness, an infection control epidemiologist at the University of Toronto.

The game has changed," he said. We're not masking to protect others from our own droplets now, we're masking to protect ourselves from people who are being lackadaisical and reckless."

Added family physician and epidemiologist Dr. Jeff Kwong: We're all so fixated on the vaccines, and definitely don't get me wrong, they're very effective. But I think the masks are just as important as the vaccine."

It's true that many may be under the impression they are no longer necessary, especially given the high vaccination rate, relatively low case counts, and patchy enforcement of mask mandates still in effect for public indoor spaces, workplaces and schools. But losing the mask is a losing proposition, say doctors and scientists.

The same as vaccination provides us with an essential base layer of immune readiness and protection, face masks are an essential top layer to prevent or reduce virus inhalation and spread between people," Tam tweeted Sunday.

Already, several regions that lifted mandatory masking policies earlier this year are being forced to bring them back to try to get cases under control. Alberta and Saskatchewan have done about-faces on their mask mandates after ending them this summer. And just last week, the Yukon government declared an emergency and announced it was bringing in new restrictions, including mandatory masking in all public indoor spaces and a proof-of-vaccination system for several public settings, amid a recent spike.

But with next to no desire among politicians and businesses for future lockdowns, combined with stalling numbers of people getting first doses of the vaccine - and a certain percentage of the population simply refusing vaccines - the responsibility for keeping oneself COVID-free is increasingly falling on individuals.

And a big part of keeping yourself safe in this new every person for themselves" environment is making sure you're not breathing in any particles of the virus in the air around you.

If it's all on us individuals now - if that's the new plan - masks become massively important because it's the last line of defence," said Furness. You can control almost nothing else about your environment or your interactions with others; you can control your use of masks."

A recent outbreak at a Barrie-area church is illustrative of what can happen if masking protocols aren't followed. According to the Star's sister paper, the Barrie Advance, there have been complaints over masking and physical distancing at Mapleview Community Church, where the local health unit said there have been 22 linked cases.

Research from around the world shows that masks, particularly surgical or medical masks, can make a big difference in cutting down your odds of contracting COVID, and dying from it.

A study published in the December 2020 edition of the American Journal of Tropical Medicine and Hygiene found that in countries where masks were the norm or supported by government policy, per-capita weekly COVID deaths increased on average by 16.2 per cent, compared with 61.9 per cent in the countries studied that did not have such measures.

One large randomized trial that included hundreds of thousands of people in rural Bangladesh, at a time when access to vaccines there was almost impossible, found a nine per cent decrease in symptomatic COVID cases in villages where cloth masks were distributed and promoted, and an 11 per cent decrease in cases in villages that had surgical masks. Mask use more than tripled where they gave them out. The findings are in a pre-print study that has been submitted to the journal Science.

We recommend that if you have a choice between a surgical or cloth mask that you choose a surgical mask, because we have stronger evidence that is effective at reducing COVID," said study co-author Laura Kwong, an assistant professor in Environmental Health Sciences at University of California, Berkeley School of Public Health.

But if you don't have a choice and a cloth mask is your only option, then a cloth mask is still better than no mask."

Kwong compared masks to seatbelts, even in areas with high vaccination rates. Why do we put on a seatbelt? Just in case."

The researchers did not test N95 masks due to cost considerations, but Kwong said KF94s, Korean masks made for the public, and the K95 mask, the Chinese version, are more affordable and accessible alternatives to the N95s.

Another study, published in August 2020 in Science Advances, tested over a dozen garden variety" types of masks and found the N95 was the gold standard" at blocking respiratory droplets, said Martin Fischer, an associate research professor in the Department of Chemistry, and Physics at Duke University, and one of the study co-authors.

The researchers found that surgical masks were the next best, while neck gaiters, bandanas and knit masks performed poorly. Most layered cloth masks did a perfectly adequate job in preventing or reducing droplet emission," Fischer added, noting people should use common sense" in evaluating masks. If it's easy to breathe through, and you can see through it if you're holding it against the light, then the performance is probably not so great."

Ontario's health officials, in their guidance to hospitals and long-term-care homes, continue to treat the virus as one that spreads primarily through large droplets and close contact as opposed to aerosols. This, despite an increasing body of research concluding that COVID is indeed airborne.

Health Canada's advice on masks has evolved with the evidence, and now includes detailed guidance on the agency's official website about what type to choose and how to wear them properly.

Linsey Marr, a leading American aerosol scientist at Virginia Tech, was one of the first to sound alarms last year about the evidence that COVID is airborne.

It's crucial to wear a mask because the way the virus is transmitted is mainly through the air by breathing it in," she told the Star. If you wear a high-performance mask, then it will remove almost all particles from the air that you breathe in. Even if there is a lot of virus in the air around you, the mask will prevent you from breathing it in."

Marr tempered her comments by noting that masks alone will not keep you completely safe. They are but one tool that can be used in combination with others - vaccines, air filtration and ventilation, physical distancing and hand washing - that together provide a powerful barrier against transmission.

Unfortunately the virus is so transmissible - the vaccines are very protective, but not 100 per cent - it looks like we still need both vaccines and masks if we want to get transmission down below a certain level."

With files from Megan Ogilvie

Kenyon Wallace is a Toronto-based investigative reporter for the Star. Follow him on Twitter: @KenyonWallace or reach him via email: kwallace@thestar.ca

May Warren is a Toronto-based breaking news reporter for the Star. Follow her on Twitter: @maywarren11