Canada’s Chief Public Health Officer is warning of the “very real” risk that new coronavirus variants could lead to a resurgence in infections as more cases of the fast-spreading variants are detected across Canada daily.
The variant threat is forcing local public-health officials to step up their COVID-19 containment measures, even as a sharp drop in overall cases since the second week of January prompts some provincial governments to tiptoe toward reopening.
The latest race to contain a variant-fuelled outbreak is unfolding in North Bay, where a cluster at an apartment tower has now spread to at least 19 residents and led to the closing of a school.
Jim Chirico, medical officer of health for the North Bay Parry Sound District Health Unit, said Tuesday that some of the infected residents of the seven-storey Skyline-Lancelot rental building had no connection to one another, raising questions about what role a more transmissible version of the virus might have played in the outbreak.
Three of the cases have come back positive for a variant on a screening test, but viral genomes still have to be sequenced to determine which variant is to blame for the cluster. The presence of the variant led Dr. Chirico to ask the Ontario government to keep his region locked down for at least an extra week.
“The shutdown is not being extended out of an abundance of caution, but because of the serious threat we’re now facing,” Dr. Chirico told a news conference. “We have community spread of the variant of concern and it is spreading quickly.”
Despite a national drop in COVID-19 cases, hospital admissions and deaths over the past month, the rise of the variants has led public-health officials to warn that the pandemic could be entering a challenging new phase.
“The risk is very real,” Chief Public Health Officer Theresa Tam said Tuesday, speaking of the variants.
Dr. Tam said Canada has now confirmed at least 381 variant cases in seven provinces through viral genome sequencing, the vast majority of them a version first identified in Britain known as B.1.1.7.
The latest estimates suggest the B.1.1.7 variant is anywhere from 35-per-cent to 45-per-cent more transmissible than the common incarnation of the virus, Dr. Tam said. A different variant, known as B.1.351 and now dominant in South Africa, is proving less responsive to vaccines, but the approved shots still seem to work well against B.1.1.7.
Quebec reported its first two cases of the B.1.351 variant on Tuesday in the Abitibi region of northwestern Quebec. Provincial Public Health Director Dr. Horacio Arruda said contact tracers linked the two cases to outbreaks in a fast-food restaurant and a party. Another 30 linked cases are under investigation.
Alberta, meanwhile, said Tuesday that retroactive testing had found a case of the B.1.1.7 variant in a COVID-positive sample from a returning traveller in mid-December, just as the significance of the variant was coming to light in Britain.
“I know there are concerns about one of these more contagious variants becoming the dominant strain in the province. This is a serious worry for me, too,” Deena Hinshaw, Alberta’s Chief Medical Officer of Health, said.
But the 104 variant cases identified in Alberta so far must be put in context, she added. Variant cases made up one quarter of 1 per cent of all cases from Dec. 15 onward.
Fiona Brinkman, a professor of bioinformatics at Simon Fraser University and a co-lead of the Canadian COVID-19 Genomics Network, said preliminary data show the vaccines currently approved for use in Canada, both of which use mRNA technology, “are so highly effective that even if they have the estimated drop in efficacy against the current variants, they would likely still be effective.”
But as Canadians wait for more doses to arrive, “we want to really slow the spread of variants,” she added.
Back in North Bay, Dr. Chirico said the apartment outbreak began when the first positive case was identified on Jan. 28 in a resident who had recently travelled. He didn’t say where the traveller – whose entire household has since been infected – had been. That first case screened positive for a variant.
Last Thursday, the health unit learned that another resident of the building who had no known connection with the first household tested positive. On Saturday, another resident of the building tested positive.
That prompted the health unit and the local hospital to send a mobile testing team to the building on Sunday. About 110 of the building’s approximately 130 residents were tested, leading to the discovery of 19 cases so far, with some test results pending.
The health unit later learned that a positive case at Sunset Park Public School was connected to the apartment outbreak, which led Dr. Chirico to shut down the school.
The North Bay outbreak isn’t the first to involve spread between residents of an apartment building who don’t live together. In December, an apartment complex outbreak involving more than 40 residents was reported in London, Ont., while a Calgary condo building saw more than 50 cases last summer.
With files from Ivan Semeniuk, Carrie Tait and Les Perreaux
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