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Non-medical masks can keep people with COVID-19 from spreading it, says Canada's top doctor

Last Updated Apr 6, 2020 at 1:34 pm PST


There's increasing evidence that people with the virus can spread it without knowing they're sick

There's also evidence that some infected people who never develop symptoms can also transmit the virus

But people wearing masks should not back off protective measures such as physical distancing and regular hand-washing

OTTAWA (NEWS 1130) — Canada’s top public-health doctor says wearing masks is a way for people who might have COVID-19 without realizing it to keep from spreading the illness to others.

That’s a change from previous advice.

Dr. Theresa Tam says the change is due to increasing scientific evidence that people with the virus can spread it without knowing they’re sick.

“It is clear that transmission of the virus is happening more often than previously recognized from infected people right before they develop symptoms,” she added.

“This is called pre-symptomatic transmission.”

There is also evidence that some infected people who never develop symptoms are also able to transmit the virus.

“This is called asymptomatic transmission,” Tam said

The role both play in driving the pandemic is not yet known.

“With this emerging information, the special advisory committee on COVID-19 has come to a consensus that wearing a non-medical mask, even if you have no symptoms, is an additional measure you can take to protect others around you in situations where physical distancing is difficult to maintain, such as on public transit or maybe at a grocery store,” Tam said.

“A non-medical mask can reduce the chance of your respiratory droplets coming into contact with others, or land on surfaces,” she added.

“So wearing a non-medical mask in the community has not been proven to protect the person wearing it. It is an additional way you can protect others.”

Nor does it mean people wearing one can back off other protective measures, including physical distancing and regular hand-washing.

Tam also said medical masks still need to be preserved for front-line health workers, so cloth masks and other alternatives are the way to go.

To date, 15,822 cases of COVID-19 have been recorded in Canada, along with 293 deaths.

Tam said most concerning are new outbreaks at hospitals and long-term care facilities, as well as cases involving people in their 20s being hospitalized.

“Although older ages are most at risk, no one can predict when critical illness will strike anyone at any age.”

Tam said, on a positive note, B.C. recorded a lower number of cases last week than the one before.

“While it is still too early to tell, this continues to encourage us that our collective action can slow the spread of this pandemic,” she said.