Alberta does not adopt federal messaging on airborne COVID-19

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Alberta updates its mask use guidelines in light of a recent change from Canada’s top doctor on the risk of airborne spread of COVID-19, but the province continues to use a one-year-old document considering transmitting aerosol virus to be a non-dominant form of spread.

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Dr. Theresa Tam, Canada’s senior public health officer, said in mid-November that respiratory aerosols – microscopic airborne particles that can carry SARS-CoV-2, the virus that causes COVID-19 – can hang in the air like smoke, which Stresses the importance of mask use and ventilation in indoor spaces as antiviral measures.

When asked on Monday how Alberta adjusted its pandemic response to reflect the updated federal message, Health Director Dr. Deena Hinshaw that Alberta had released a document in November 2020 that identified risk factors for airborne proliferation that have been used to shape the province’s public health decisions.

This document states that aerosol dispersal “has not been shown to be a predominant mode of transmission for COVID-19” and adds that aerosols are only known to contribute to virus spread in two areas: health environments where aerosol-generating medical procedures are performed, and prolonged indoor community gatherings with limited ventilation involving activities such as vigorous exertion or singing, which may increase the number of respiratory particles released. Hinshaw said this guide is still in use.

“Ultimately, the aerosol-type transmission information we released a year ago is still very important,” she said Monday.

Hinshaw said Alberta has been working to update its masking guidelines following updated federal advice last month that recommended Canadians at high risk for COVID-19 infection wear a medical face mask instead of non-medical drug masks. Alberta Health did not respond to a request for a copy of the updated provincial guidance.

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Alberta Health Services said Monday it continues to work with health care unions to establish guidelines for the use of personal protective equipment including masks among their staff.

The current agreement between the health authority and four health professionals gives front-line workers the power to choose which PPE they want to use based on a point-of-care risk assessment and their professional assessment, which means they can choose whether to use N95 respirators or medical masks.

University of Calgary Expert in Infectious Diseases, Dr. Daniel Gregson, said that it has been known for some time that COVID-19 can be spread in the air over a distance greater than two meters. But he said only about 10 percent of people infected with COVID-19 contribute to airborne proliferation, while the majority of people produce droplets. The difference may depend on a person’s viral load, research suggests.

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The predominant form of spread of COVID-19 in society is “probably” airborne, Gregson said, with a small subgroup of individuals likely to be responsible for many infections. He said there is strong evidence that masks are effective in preventing spread in well-ventilated spaces, citing a relative lack of recorded transmission on aircraft.

“The general ethos is that an N95 mask will prevent you from starting to get infected with high security, but you can not wear them for a long time. The regular surgical masks are pretty good, and so are these non-medical masks. not as effective, but they work in practice, “said Gregson.” The mask, more importantly, probably prevents you from transmitting before you have symptoms. “

A recent advocate for parents in Calgary has called for increased air filtration and ventilation to prevent airborne spread of COVID-19 in schools, including by installing HEPA filters.

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Gregson said tools to improve ventilation such as HEPA filters could help reduce the risk of COVID-19 spread, but said the measure should be secondary to pediatric vaccination efforts.

“We have a vaccine now for children and the vaccine will be more effective than anything else to do with airflow,” he said. “It will be the most important way to prevent infection in schools.”

Alberta Health spokeswoman Lisa Glover said in a statement that ventilation is “one of a number of factors” that need to be considered when spreading COVID-19, with the province recommending maintenance of ventilation systems to keep them functioning optimally.

jherring@postmedia.com

Twitter: @jasonfherring