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Canada may see 4th COVID-19 wave if restrictions eased too quickly, experts warn

Click to play video: 'Optimism rises about summer despite concerns of potential 4th wave' Optimism rises about summer despite concerns of potential 4th wave
WATCH: As Canada gradually emerges from the third COVID-19 wave, some people are wondering if there will be a fourth wave. Eric Sorensen reports on why experts say a fourth wave would be less threatening, and how there's cautious optimism about the summer ahead – May 18, 2021

As new coronavirus cases in Canada continue to decline and vaccinations ramp up across the country, Canadians are left wondering if the third wave of COVID-19 is behind them – and whether another surge is expected later this year.

Monday saw the lowest national daily count — 4,586 new cases — since March 29, right before infections surged to record levels in mid-April. Deaths in the country reached 25,000 Tuesday.

Read more: Canada’s COVID-19 cases continue to plunge, but some provinces still struggling

Click to play video: 'COVID-19 vaccine rollout progresses but increased hospitalization still a concern' COVID-19 vaccine rollout progresses but increased hospitalization still a concern
COVID-19 vaccine rollout progresses but increased hospitalization still a concern – May 17, 2021

With some provinces still grappling with high infection rates and hospitalizations, the third wave is “definitely not over” but the country is “headed in the right direction,” said Isaac Bogoch, an infectious diseases specialist at the University of Toronto.

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“We’re certainly on the downslope of the third wave, but depending on where you are in the country, there’s still a lot of cases of COVID-19,” he told Global News.

Tight restrictions, including lockdown measures and stay-at-home orders, are currently in place in most provinces.

However, once those measures are eased and people start gathering, experts say, it is possible that cases will climb back up again.

Click to play video: '75% of Canadians will get 1st shot of COVID-19 vaccine this summer: Trudeau' 75% of Canadians will get 1st shot of COVID-19 vaccine this summer: Trudeau
75% of Canadians will get 1st shot of COVID-19 vaccine this summer: Trudeau – May 18, 2021

“There is a lot of fear right now that if we reopen too soon, that we could trigger a fourth wave,” said Samir Sinha, director of geriatrics at Sinai Health and University Health Network hospitals in Toronto.

Sumon Chakrabarti, an infectious diseases physician at Trillium Health Partners in Mississauga, Ont., said he “fully expects” a fourth wave in the fall.

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But according to Gerald Evans, chair of the infectious diseases division at Queen’s University in Kingston, Ont., a fourth wave though not inevitable, could take place if there is poor vaccination uptake, emergence of a major variant with resistance to vaccine-induced immunity and public health restrictions are lifted too quickly.

What could a fourth wave look like?

By summer, as millions more vaccines funnel into the country, there’s a chance for restrictions to lift but there’s a caveat — 75 per cent of those eligible for vaccines need to have one dose, and 20 per cent need a second, according to a new roadmap by the Public Health Agency of Canada (PHAC).

As of Tuesday, 46 per cent of the Canadian population has received at least one dose of an approved vaccine, according to the COVID-19 Vaccination Tracker.

Read more: Potential 4th wave of COVID-19 could hit Canada’s youth: expert

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With a greater percentage of people vaccinated, especially among the older age groups, the fourth wave when and if it hits, will put less burden on the health-care system compared to the first three, experts say.

“What’s changed now is with widespread vaccination as well as immunity from people who have been infected previously, the chances of people getting hospitalized are much less,” said Chakrabarti.

Bogoch agreed, saying if cases do increase over time, those infected are less likely to land in hospital and have a significant negative impact on society. There is also a lower chance for the unvaccinated younger population to get sick, easing the pressure on hospitals.

Starting Tuesday, all adults aged 18 and older in Ontario are eligible to book an appointment for a vaccine.

Canada has authorized the Pfizer-BioNTech COVID-19  vaccine for anyone aged 12 and over, becoming the first country in the world to extend this approval to children.

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Quebec is aiming to vaccinate adolescents aged 12 to 17 by the end of the school year next month. Meanwhile, Alberta opened up bookings for this age group on May 10 and British Columbia will also start vaccinating children around the province over the next few months.

A summer fourth wave would be “much smaller” because of the vaccine rollout and seasonal forcing, Evans said.

If many people have first dose vaccinations  … it may not be as catastrophic as previous waves that we’ve seen before,” Sinha added.

Can a fourth wave be averted?

Canada has seen a 25 per cent decrease in reported active cases since the peak of the third wave in April, according to Theresa Tam, the country’s chief public health officer.

Despite the steady progress, public health officials are urging caution amid the spread of more transmissible variants.

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Read more: ‘Game-changer’: How mRNA COVID-19 vaccine technology could help fight other diseases

On May 14, citing evidence of increased transmission, PHAC designated the B.1.617 variant that was first reported in India as a variant of concern (VOC) after first being listed as a variant of interest.

This is in addition to the variants that were first detected in the United Kingdom (B.1.1.7), South Africa (B.1.351) and Brazil (P.1). As of Tuesday, more than 177,782, cases of VOC had been reported across all 10 provinces.

In the U.K., the sub-lineage B.1.617.2 is already threatening reopening plans, with scientists warning it was more transmissible than the country’s main strain.

Click to play video: 'Could variants threaten reopening plans?' Could variants threaten reopening plans?
Could variants threaten reopening plans? – May 17, 2021

“With variants in play while vaccinations are going up, we have to be very cautious about that downward path,” said Tam during a news conference on Tuesday.

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“Maintaining our progress to reduce infection rates down to manageable levels, ease pressure on the health system and re-establish public health policy will put us in a better position to prevent a fourth resurgence,” she added.

Read more: Indoor COVID-19 restrictions could ease by fall if 75% are fully vaccinated: PHAC

Prime Minister Justin Trudeau said things can’t open back up until cases are way down.

“Otherwise we risk a fourth wave,” he said Tuesday.

Creating safer indoor spaces and vaccinating as quickly as possible will be important to avoid another spike in infections, said Bogoch.

Sinha said public health authorities will need to find a balance between making sure that more shots get into people’s arms and reopening “very slowly and in a responsible way,”

“We still have a long way to go before we can consider ourselves to be out of the woods,” he said.

— With files from Global News’ Katherine Aylesworth

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