Canada’s top doctor has been hesitant to say tiny airborne particles are spreading COVID-19. Under pressure, she reconsiders


OTTAWA – Canada’s top public health official says it may be time to revise federal guidelines to provinces on how to prevent airborne infections with COVID-19.

Director of Public Health Dr Theresa Tam said on Tuesday that the science of whether COVID-19 is transmitted via tiny aerosolized particles indoors “is evolving” and other changes for protecting healthcare workers, especially in long-term care homes, may be necessary.

It’s a small but controversial concession from Tam, who is under pressure from an increasingly vocal group of Canadian nurses and some infectious disease specialists – a concession that could lead to stricter requirements for respirators. N95 expensive, not only for hospitals and long-term care homes. , but also for stricter rules in public workplaces outside healthcare establishments.

His statement comes months after the US Centers for Disease Control and the World Health Organization recognized that airborne transmission of aerosolized particles may be possible in crowded and poorly ventilated environments.

Tam’s reluctance to definitively agree that there is airborne transmission can be disconcerting to some, but epidemiologist Dr David Fisman of the University of Toronto’s Dalla Lana School of Public Health says he it is difficult for him to reach a consensus.

“Dr. Tam has to negotiate a very difficult medico-political landscape, which prevents him from simply saying what many of us now take for granted, ”Fisman said.

“The complexities of this situation are really closely tied to the N95 supply chain and fear that it will dry up,” he said. “And also to some very well established voices in the Canadian infection control scene who are adamant that this disease cannot be transmitted by aerosol.

The virus is believed to be spread mainly from person to person through larger droplets that are spread when people cough, sneeze, talk, sing or cry. These droplets are believed to fall within two meters – hence the recommendation to wear a mask, keep physically separate, wash your hands frequently, and not touch your face.

Tam told reporters on Tuesday that there was more “science and data” emerging, and she believes smaller particles of airborne virus that have exhaled and may remain airborne for many years. long periods “exist”. But she said that “the circumstances and their significance are still being worked out.

Even in the absence of certainty in the data, Tam said she had previously recommended universal masking policies in healthcare settings because of the risk that healthcare workers face from asymptomatic or presymptomatic people.

Now, she said, “given the evolution of opinion and evidence, we will of course go back and consider again whether any aspects of the guidelines need to be reviewed as well.”

Federal guidelines to provinces already recommend droplet and contact precautions for routine care of patients with COVID-19. It requires N95 respirator masks and personal protective equipment for healthcare workers whenever aerosol-generating medical procedures are performed, such as intubating a patient.

Canadian nurses have called on Tam and the Public Health Agency of Canada to update this federal notice to establish even stricter rules based on the “precautionary principle” that would oblige employers in care facilities active and long-term care personnel to equip themselves with N95 and PPE whenever workers come into contact with COVID-positive patients.

“Federal guidelines don’t go far enough,” Linda Silas, president of the Canadian Federation of Nurses, said in an interview Tuesday.

Silas said that even now – 10 months after the start of the pandemic – there are hospitals in Ontario and Alberta that do not mandate the wearing of N95 respiratory masks for nurses entering units with COVID-positive patients. .

Health workers can do a ‘point-of-care risk assessment’ and if they believe there is a risk to a patient who, for example, cannot be masked and is coughing or vomiting, the nurse or the personal support worker may request an N95 be provided.

Still, Silas said some directors were still reluctant to waive them as obvious.

The problem, she said, “is the cost and the fear of the supply running out.”



Tam said on Tuesday she was looking to update the ventilation recommendations. She said modern hospitals usually already have good ventilation; in the meantime, she said HVAC systems should be maintained.

And Tam said to everyone, “hide indoors when you’re not with people in your household and certainly when you can’t maintain any sort of distance” and “improving ventilation would be the kind of circumstance. where you can reduce the impact of aerosols. “

Tam said on Tuesday she was “very excited” to bring together ventilation experts, infectious disease experts and infection control practitioners “to see if we might not be able to find the most scientifically informed and more sensible ”.


Please enter your comment!
Please enter your name here