COVID-related hospitalizations at a low point but BA.2 subvariant is driving new infections: modelling

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New federal modelling released today suggests there will be an increase in COVID-19 cases in the coming weeks because the much more infectious BA.2 subvariant is circulating widely.

While the number of cases is expected to rise, Canada’s chief public health officer said the national response to this sort of increase in disease activity will be different now than it has been in the past.

“We are now in a period of transition, and we anticipate that progress will not be linear and that there will likely be more bumps along the way, including resurgence in cases this spring,” said Dr. Theresa Tam.

“However, with higher levels of population immunity, proven protective practices to slow the spread and reduced pressure on the health system, we are in a stronger position to get back to more of the things we love, while continuing to keep each other safer.”

Elevated case counts were not unexpected, Tam said, given the federal government and the provinces and territories have been dismantling COVID-19 restrictions and pushing ahead with a lighter touch on public health measures to curb new infections.

Tam said Friday the number of COVID-related hospitalizations and deaths is at a low point, thanks to strong vaccine coverage and natural immunity from past infection.

‘Disease activity remains elevated’: Tam

Since January, the number of people in hospital with the novel coronavirus has dropped by half, to roughly 5,000 people nationally on any given day. The number of daily deaths reported is also about half of what it was just two months ago with well under 50 deaths reported nationwide each day.

That could change in the coming weeks, Tam said, because there has been an uptick in case counts because of BA.2, an Omicron offshoot.

A vial of the Novavax coronavirus vaccine is pictured in London, U.K. Shipments of the protein-based vaccine started arriving Canada this week. (Alastair Grant/AP Photo)

As she presented the modelling data, Tam said “disease activity remains elevated and is rising in some parts of the country” and “hospitalization trends could rise” as a result.

WATCH: Tam discusses reasons for the resurgence of COVID-19 in parts of Canada

Tam discusses reasons for the resurgence of COVID-19 in parts of Canada

Canada’s Chief Public Health Officer Theresa Tam says that whenever public health measures are relaxed, a resurgence of COVID-19 cases can be expected. Tam says she encourages people to continue wearing masks to keep the pandemic under control. 1:45

Early research suggests BA.2 is five to seven times more transmissible than the original COVID-19 strain first detected in Wuhan, China, or roughly two times more transmissible than the Delta variant, which first hit in late 2020 and early 2021.

While BA.2 will result in more severe cases reported, Tam said the impact on the health care system is expected to be more “manageable” than with previous waves.

Tam said that moving forward, the likely scenario is that Canada will experience “low to moderate ongoing virus transmission” with “intermittent” waves driven by new variants and reduced immunity — a more “predictable” pattern that likely can be handled without restrictive public health measures.

Planning for various scenarios

However, the Public Health Agency of Canada (PHAC) is also preparing for a “worst-case scenario” in which a new, much more vaccine-resistant variant emerges that causes widespread severe disease.

That sort of scenario would demand a return to more restrictions and stepped-up “personal protection practices.”

With COVID-19 testing capacity severely restrained in most areas, the federal government has been relying on other metrics to determine the trajectory of the virus.

PHAC has a number of sites nationwide where it is monitoring wastewater to determine transmission trends.

The results so far paint a mixed picture.

In Ottawa, for example, wastewater readings suggest virus activity has never been higher. But at sites in Saskatchewan, signals are declining.

Tam said that all Canadians, regardless of where they live, should get their booster shots or — if they’re still holding out — the primary series of the COVID-19 vaccine.

Even if someone has had an infection, they should still get that third shot three months after the onset of symptoms, Tam said, because the booster dose offers much more “substantial” protection against Omicron, including BA.2.

“There’s some gaps in our booster coverage,” Tam said.

According to the PHAC data, only 57 per cent of people over the age of 18 have had a third dose — 30 percentage points lower than the share of the population that has received two doses.

“Any adult over 18 years of age, when you’re eligible, go get the booster now. Get the booster,” she said. “Keeping COVID-19 vaccinations up to date is one of the best ways to protect ourselves and to collectively reduce the impact of future waves.”

For people reluctant to get an mRNA vaccine like those offered by Pfizer or Moderna, Tam said, there is the Novavax product, a protein-based vaccine that will soon be available in Canada. On Thursday, the federal government started receiving some of the 3.2 million doses it has ordered from the Maryland-based company and distribution to the provinces and territories is now underway.

The hospitalization numbers reveal just how much more susceptible the unvaccinated are to severe outcomes.

Fully vaccinated people with a booster dose were ten times less likely to be hospitalized than the unvaccinated.

People vaccinated with just two doses were also less likely to need medical care — their hospitalization rate was four times lower than the unvaccinated between mid-February and mid-March, according to PHAC data.

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