Clinical lead nurse James Widjaja swabs Jennifer Eriksson during a mandatory COVID-19 test at Toronto Pearson International Airport's Terminal 1 on Feb. 1, 2021.Fred Lum/The Globe and Mail
A preliminary look at all cases of COVID-19 that were reported in Ontario during a single day last month has determined that 5.5 per cent of those cases examined so far were caused by the new U.K. variant of the coronavirus. Of those, 89 alone were connected to a large outbreak of the variant at the Roberta Place long-term care facility in Barrie.
However, the study also identified an additional 16 cases of the British variant in Ontario that were not connected to Roberta Place. Three are known to be individuals who recently travelled internationally. The provincial lab said it does not have enough information from local public health units to know if the other are associated with recent travel or not.
The result is a further indication that the British variant is likely to be circulating in the Ontario population, albeit at a low level. Because it spreads more easily, disease modellers predict the variant could drive a new surge in COVID-19 cases in as little as four to six weeks if public health measures are not sufficient to contain it.
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“We recognize that the doubling rate of this variant has been shown... to be quite high. Essentially, a doubling is expected approximately every one to two weeks,” said Vanessa Allen, chief of microbiology and laboratory science for Public Health Ontario, who presented the results at a news briefing on Thursday.
The viral samples gathered for the study were all obtained from cases that were reported on Jan. 20, the day chosen for a provincewide snapshot to reveal the frequency of the new variants. So far, 1880 of an expected 3003 samples from COVID-19 cases reported that day have been screened for the presence of a genetic mutation that is found in the British variant, as well as two other variants of concern associated with South Africa and Brazil.
The 103 variant cases detected from samples taken that single day bring the provincial total up to 152 cases overall since the British variant was first detected in Ontario in late December. One case of the South African variant has also been identified in the province.
Of those that were identified from the Jan. 20 snapshot, the 16 cases that were not connected to the Roberta Place outbreak show a pattern of susceptibility to the variant that is evenly divided between males and females and spread across all age groups. Three out of the 16 were under the age of 19. When the variant first emerged in Britain, experts there noted that cases grew proportionally faster among young people – a group that has previously tended to show lower incidence of COVID-19.
Troy Day, a mathematical biologist at Queen’s University who is part of an expert group advising the province on modelling the pandemic, said the number of cases outside of the Roberta Place outbreak was too low to project precisely if and when there might be a surge in which the variant becomes responsible for the majority of cases in Ontario.
He added that the number was high enough, however, to be concerned “there’s some level of transmission under the surface that we’re not really aware of at this point.”
Irfan Dhalla, a physician and vice-president with the Unity Health network of hospitals in Toronto, said that given the risk posed by the new variant, the province is effectively dealing with two separate pandemics at the same time. As the new variant represents a greater threat relative to the more common form of the virus, any cases in which a variant is identified should be prioritized for contact tracing, case management and other measures that could prevent further spread, he said.
Dr. Dhalla, who co-chairs a federal task force on COVID-19 testing, said he was strongly in favour of Ontario’s decision to begin screening all positive cases for the variant as of Wednesday. He added that increased testing, which the panel has recommended, should also be prioritized in areas where cases of the variant are turning up in community spread.
Variants are also beginning to appear in great frequency in other provinces. On Thursday, Alberta’s Chief Medical Officer of Health, Dr. Deena Hinshaw, reported 11 new cases of the British variant – seven of which have no link to travel. The number brings that province’s total up to 68.
- with a report from James Keller
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