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Risk-assessment tool for fully vaccinated people coming to Canada as Delta variant dominates U.S.

Last Updated Jun 23, 2021 at 6:51 am PDT

Dr. Theresa Tam says the Delta variant adds new risks, full vaccination doesn't guarantee people won't get COVID-19, and it's hard to know who is vaccinated and who is not. Fusion Medical Animation

Science shows that only 33% to 50% protection is afforded against the Delta variant with one vaccine dose.

A UK study found that 2 doses of Pfizer's shot are 96% effective against the Delta variant at preventing serious illness

OTTAWA – Chief public health officer Dr. Theresa Tam says she’ll soon have the advice to inform fully vaccinated Canadians to figure out what they can safely do, but she says much will depend on who you are and where you live.

More than 7.5 million Canadians, or 20 per cent of the entire population, have now received both doses of a COVID-19 vaccine but there is still no guidance on what that means for personal behaviour.

The Centers for Disease Control (CDC) in the United States issued its first advice for fully vaccinated Americans in early March when less than 10 per cent of the U.S. population had all required doses.

That initial advice included being able to visit safely with other fully vaccinated people, including indoors, without masks or physical distancing.

“These risk assessments depend on your individual risk, who you’re about to get into contact with, as well as the epidemiology of your specific community,” said Tam.

But Tam says the Delta variant adds new risks, full vaccination doesn’t guarantee people won’t get COVID-19, and it’s hard to know who is vaccinated and who is not.

She says a risk-assessment tool for Canadians is being developed with provincial and territorial health officials and she is urging Canadians to keep following local public guidance and knowledge about their own risks from COVID-19.

Dr. Tam’s comments arrive the same the U.S. confirmed the Delta variant, which was first detected in India, now represents more than 20 per cent of coronavirus infections in the country in the last two weeks.

That’s double what it was when the CDC last reported on the variant’s prevalence.

Dr. Anthony Fauci, the nation’s top infectious disease expert, warned that the U.S. could be following the United Kingdom’s course, where the variant has become the dominant strain due to rapid spread among youth.

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Fauci says indications are that the COVID-19 vaccines remain effective against the variant.

Dr. David Fisman, a member of Ontario’s Science Advisory Table, said Tuesday that the effective reproduction number (Rt) of the Delta variant is now over 1 in Ontario, which indicates exponential growth.

“Dynamics have changed. Get vaccinated. We will likely see a resurgence with Delta, but can blunt the impact with widespread vaccination,” he tweeted.

Dr. Tam says the country has already met its first vaccination benchmark. But with the more contagious Delta variant poised to become more prevalent, she says people still need to remain vigilant.

“Now, based on the latest unofficial numbers, we have already surpassed our initial target of over 75 per cent of the population 12 years and older with at least one dose and at least 20 per cent fully vaccinated,” said Tam.

“But this is not the place to stop.”

The Alpha variant, first detected in the UK sometime last year, is 50 per cent more transmissible than the original COVID-19 strain, The Delta variant, first detected in India, is at least 40 per cent more transmissible than Alpha.

A recent study in the United Kingdom found that two doses of the Pfizer vaccine are 96 per cent effective against the Delta variant at preventing severe COVID-19 requiring hospitalization.

In contrast, one dose offers roughly 34 per cent protection against the Delta strain.

After reporting over 800 cumulative cases of the Delta variant on Monday, the province says there are now 916 confirmed cases of the mutation.

With files from The Canadian Press