COVID-19 is spread through the air. Here’s what you can do this winter

The Public Health Agency of Canada (PHAC) now recommends opening windows to increase ventilation and use HEPA filters purify the indoor air, but he stops before pleading for better quality masks or say bluntly that the virus is mainly airborne.

“From what I’ve seen, Canada is now an outlier in terms of not recognizing airborne transmission,” said Linsey Marr, virus transmission expert at Virginia Tech in Blacksburg, Va. . “I think the message could be clearer.”

Canada’s masking guidelines have also not been updated for over a year, with non-medical masks containing a filter still recommended – despite research showing that sheet masks are less efficient than surgical masks against the airborne spread of COVID-19.

“It looks like they always talk like there’s a shortage of medical masks,” said Marr, professor of civil and environmental engineering. “We know any mask is better than no mask, but some masks are better than other masks as well – and so if you haven’t already, you may want to consider upgrading your mask. “

Marr said Canada was “missing” the opportunity to promote better protection against medical masks with higher filtration levels, like surgical masks or N95s, but also when it comes to explaining exactly why filtration, ventilation and masking are so important.

“It’s because the virus is in the air,” she said. “I think if people understand this they will be much more likely and willing to take effective steps to reduce transmission.”

Aerosol transmission “changes the game” on indoor risk

Almost two years after the start of the pandemic, our understanding of the aerial spread of the virus has changed dramatically, with more infectious variants increase the risk and physical distancing alone did not turn out to be enough – especially indoors.

The virus can be transmitted through the air in two main ways: microscopic airborne particles called aerosols that linger in the air like smoke, or larger respiratory droplets that quickly fall to the ground (prompting the original guidelines from physical distance of two meters).

But experts say Canada’s public health guidelines have struggled to keep up with evolving science, leading to conflicting advice, such as PHAC recommendation that physical distancing is the “best way to help prevent the spread of COVID-19.”

“If this is the case, then you should be okay with being in a room with a person infected with COVID without your mask if you are six feet apart,” said Raywat Deonandan, epidemiologist in global health and associate professor at the University of Ottawa. .

“If not, then you are accepting aerosol transmission. But the problem is, we don’t have 100% consensus among the experts. So it can be confusing for people who get conflicting information. . “

Toronto pulmonologist Dr Samir Gupta said once we realized aerosol transmission was the primary driver of the virus’s spread in the air, public health guidelines for Canadians should have followed suit. not.

“This whole pandemic has turned aerosol science upside down,” he said. “It became clear that there were transmission events occurring much further than two meters away, so it couldn’t just be droplets.”

Gupta said the “pendulum has swung” towards aerosol transmission being a major factor in how the virus is transmitted, and the practical implications of this are “huge” for the Canadian public when it comes together at the interior.

“You can be very far from the source of infection, but if you stay there long enough you will catch it through aerosols,” he said. “And that is a game-changer in terms of controlling the spread.”

Overlapping protectors can “significantly reduce the risk”

Other countries go far beyond Canada’s guidelines: U.S. Centers for Disease Control and Prevention now say N95 can be worn by the general public, and Britain recently launched a awareness campaign on prevention of indoor air transmission.

Canada has quietly updated its guidelines on the risk of airborne spread a year ago, adding the word “aerosols” for the first time, but he stopped before recommending medical masks for the general public or creating a similar campaign specifically around the spread by air.

“It is both disturbing and tragic that our public health leaders have repeatedly failed to protect Canadians through simple, cost-effective and proven airborne protection measures,” said Mario Possamai, forensic investigator and senior advisor on the issue. 2007 SARS Commission.

“They should be held responsible for the deaths and infections their shameful neglect has caused.”

WATCH | How delays in recognizing airborne transmission of COVID-19 put lives at risk:

How delays in recognizing airborne COVID-19 transmission put lives at risk

A review of the timing of Ontario’s response to COVID-19 and how the delay in recognizing the risk of aerosol transmission may have cost lives, despite lessons learned from the 2003 SARS outbreak. 8:51

Experts say that the layering of different levels of protection, also called the Swiss cheese model, can further prevent the spread of COVID-19 as the colder weather pushes us more towards indoor activities in the weeks and months to come.

“None of them are 100% effective,” said Marr of Virginia Tech. “But when you combine them, you can significantly reduce the risk.”

Deonandan stated that the use of suitable masks, ventilation and filtration – combined with high vaccination rates and vaccine passports for indoor spaces – will help keep transmission levels low and address the “lion’s share of the risk”.

“A year ago there were so many mysteries about this disease… but now it’s not so mysterious how people get it – and because we know it, we know how to stop it” , did he declare.

“So we don’t need to have blockages anymore, we don’t need to have economic pain anymore. All we have to do is make good choices every day.”

Elevator measures cautiously, like “an on-off switch”

High vaccination rates, rolling out third doses to vulnerable Canadians, and approving vaccines for children over the next few weeks will make a big difference to our risk levels for COVID-19 across Canada, but experts say that we have to be patient.

“When cases are low, that doesn’t mean we just need to remove these measures,” said Dr. David Fisman, an epidemiologist at the University of Toronto’s Dalla Lana School of Public Health. “It’s like folding your umbrella in a rainstorm because you’re not wet yet. “

Ontario recently announced its intention to lift all its COVID-19 public health measures by March – including masks – but experts say the decision should be tied to data on transmission levels circulating at the time.

“If we are to lift the rules… we also have to be prepared to reinstate them if a new, more transmissible variant comes along that escapes the vaccine,” Marr said.

“I think the United States got in trouble lifting mask rules in may, and we had no way of bringing them back when we really needed them with the wave of [the delta variant] at the end of summer. “

Marr said keeping the precautions in place and using a “data-based masks policy” tied to transmission rates in the community “as an on-off switch” will help prevent a resurgence of COVID- 19 in the future as we continue to learn to live with the virus.

“It is important that people understand that the crisis is not over, but it will be,” Deonandan said. “And I know you’re sick of hearing this, but we can live our lives now, but live our lives responsibly.”