COVID-19 hasn't gone anywhere in Canada — and we could still see another surge
Spike in global cases, spread of BA.2 subvariant raise concerns for Canada
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COVID-19 may no longer be top of mind for Canadians, but there are still more cases and hospitalizations now than at some of the worst points of the pandemic — and while we may have moved on, the virus definitely hasn't.
Canada has lifted almost all public health measures as COVID-19 levels continue to drop from the peak of the devastating Omicron wave that overwhelmed testing capacity and fuelled a record surge in hospitals across the country.
But a recent rise in global COVID-19 cases, the spread of a more contagious Omicron subvariant and a spike in early surveillance signals across Canada has experts increasingly worried we could be on the verge of another surge.
"Following several weeks of declining activity nationally, the average daily case counts are now levelling off," Canada's Chief Public Health Officer Dr. Theresa Tam said during a news conference Friday.
"As public health measures ease, increased levels of transmission are not unexpected since the SARS-CoV-2 virus is still circulating widely."
'This is not over yet'
A steep drop in testing across much of the country has blurred the picture of how much the virus is circulating, yet other metrics such as wastewater data and hospitalizations suggest COVID-19 levels remain higher than at many other points in the pandemic.
More than 4,000 Canadians are currently hospitalized for COVID-19, and although that total has been dropping from a January peak, it's still the highest since April 2021 — and almost as high or higher than the peak of every other wave.
"Even though we're in a much better place now than we were one and two months ago, there's still a lot of COVID around and there's still a lot of people in hospital with COVID," said Dr. Isaac Bogoch, an infectious diseases physician at Toronto General Hospital and member of Ontario's COVID-19 vaccine task force.
"Sadly, this is not over yet."
The silver lining for Canada is that our combination of high vaccination rates and infection-based immunity will ensure most Canadians are protected against serious illness.
Yet the highly-contagious Omicron variant — including the BA.2 subvariant that's on track to dominate new cases — is proving able to infect people more easily than its predecessors.
Measuring booster protection
There are also concerns over waning immunity, with studies showing protection from infection can decline within months even after a booster — while protection against hospitalization appears to be holding up.
A recent report from the U.S. Centers for Disease Control and Prevention (CDC) found protection from infection dropped from 69 per cent within two months of a second dose to just 37 per cent after five months.
That protection increased to 87 per cent with a booster, but dropped down to 66 per cent between four and five months and fell to just 31 per cent after five or more.
A new CDC report released Friday suggests boosters can still prevent hospitals from being overwhelmed, finding those who received three doses were 94 per cent less likely to be put on a ventilator or die from COVID-19 compared to those who are unvaccinated.
But while boosters are still remarkably protective against severe illness, less than half of Canadians have received one.
"Our third shot coverage is still lower than in many other jurisdictions, and Omicron in any case infected lots of people who'd had three shots," said Dr. David Naylor, who co-chairs the federal government's COVID-19 Immunity Task Force.
"It's likely that the Omicron tsunami did provide a pretty substantial boost to background immunity for lots of Canadians. What's not clear, however, is how much immunity is conferred by a mild case of COVID-19 due to Omicron and how long that protection lasts."
That could be a key factor in whether Canada can avoid a major uptick in hospitalizations in the weeks ahead, Naylor said, but there's still a possibility we may be in for an "ugly spring."
"We might have a wave or a smaller wavelet. The extent to which this impacts us in Canada is not really known," Bogoch added.
"While we do have some good community level protection, is it good enough to stop hospitals from filling up again? I'm not sure."
Wastewater signals increasing in Canada
In Ontario, where PCR testing access is now extremely limited — making it tougher to figure out accurate infection rates — the province's COVID-19 Science Advisory Table recently reported a slight uptick in concentrations of SARS-CoV-2 through wastewater surveillance.
Based on that case growth, the table estimates the current daily number of infections is anywhere from 15,000 to 20,000 and expects hospital occupancy to rise, though not to the crushing levels of earlier waves.
There's a recent upturn in wastewater data from Calgary as well, while in Saskatoon, the wastewater virus load increased by 5.4 per cent by March 9 when compared to the weekly average of the previous week, University of Saskatchewan data shows.
That Saskatoon data also shows the BA.2 subvariant made up more than 42 per cent of the latest reported virus load — slightly higher than its fellow subvariant, BA.1 — and the university now expects BA.2 will likely "completely overtake" BA.1 over the next few weeks.
Meanwhile on the east coast, P.E.I. public health officials say positivity rates at test centres are rising, while Newfoundland data shows cases began going up again in just the last few days.
Global rise in COVID-19 'stark reminder' to Canada
New infections have jumped by eight per cent globally compared to the previous week, World Health Organization data shows, with 11 million new cases and just over 43,000 new deaths reported between March 7 to 13 — marking the first spike since the end of January.
The biggest jump was in the Western Pacific region, which includes South Korea and China, where cases rose by 25 per cent and deaths by 27 per cent.
Many European countries are also experiencing a rise in cases. In Denmark, a BA.2-driven surge began in February, while the U.K. is now seeing rising infection rates and hospitalizations — both up at least 20 per cent from last week — following the end of the country's pandemic restrictions.
WATCH | COVID-19 cases surge in Asia, Europe as public health measures relax
"Watching what's going on in terms of case numbers in Europe, I think should be certainly a bit of a stark reminder that the virus has not disappeared," said Jason Kindrachuk, an assistant professor of viral pathogenesis at the University of Manitoba in Winnipeg and Canada Research Chair of emerging viruses.
"BA.2 should, in my mind, kind of reinvigorate us to realize we're not through with this yet and in fact the virus can still change."
Canada remains a unique situation, given its underlying population differences and vaccination rates, Kindrachuk said, which could mean things play out differently here.
"But we have throughout the pandemic also seen that things that have happened in Europe have ultimately then moved into North America," he said.
"And we've had a bit of time lag where we at least can start to try and prepare."
The latest available data shows BA.2 accounts for 22 per cent of cases in Canada and estimates are that it spreads roughly 30 per cent more easily.
Tam said it will likely become the dominant strain in Canada in the coming weeks but so far it's been increasing at a "slow rate" here — likely due to a combination of vaccination and prior infection.
"What it will do is seek out pockets of the population where the immunization rates are lower, where people haven't been boosted and where there hasn't been a lot of [Omicron infection] — those are the at-risk populations," she said.
Dr. Lisa Salamon, an emergency room physician with the Scarborough Health Network in Toronto, said communities that are lagging behind on vaccinations, and those featuring lower-income residents in crowded housing or multi-generational homes, remain more at risk of household transmission and dire outcomes.
"My concern is, locally, there are going to be places that are overwhelmed that people just don't care about," she said.
"The general population doesn't care if it doesn't impact them."