B.1.1.7 variant cases growing quickly

More aggressive strain will become dominant in Ontario, experts warn

The spread of the B.1.1.7 variant of COVID-19 in Ontario has seen an average daily growth rate of nearly 13 per cent since late January, a new Star analysis finds, prompting infectious disease experts to urge vigilance when it comes to following public health measures.

The Star’s analysis of publicly available data shows that Peel, York, Durham and Toronto have led the GTA in average daily growth in B.1.1.7 cases since Jan. 28, the date the province started reporting variant cases.

So far, health officials have confirmed fewer than 300 B.1.1.7. infections in Ontario, providing a very small sample size for analysis. However, the provincewide increase from about 50 cases in late January to 275 as of Thursday is in line with public health warnings about the variant’s greater transmissibility.

Since reporting began, cases of the variant have grown at an average daily rate of 16 per cent and 8.5 per cent in Peel and York regions, respectively, while Durham has seen its total grow by an average of 6.5 per cent per day. Toronto is just below that at an average daily growth rate of 6.3 per cent. This comes just four days before schools in Peel, York and Toronto are slated to reopen for in-person classes on Tuesday.

The available data is preliminary and does not necessarily indicate exponential growth. But Dionne Aleman, a University of Toronto professor and expert in pandemic modelling, said Ontarians need to be more cautious with interactions they have with people outside their households, given that early studies show B.1.1.7 to be about 50-per-cent more transmissible than previous variants.

“It is premature to be reopening businesses and schools in areas that have any sort of significant community spread of COVID because if there’s spread of COVID, almost certainly there are some people that have the B.1.1.7 variant,” she said. “We’re going to end up either in lockdown again or pushing our health-care system back to the absolute brink again.”

According to the latest projections from Ontario’s COVID-19 Science Advisory and Modelling Consensus Tables, Aleman’s fears are not without merit. On Thursday, the group held a briefing to update reporters on its latest projections, which noted that B.1.1.7 cases likely make up between five and 10 per cent of Ontario’s cases, and that the variant will soon become dominant.

To prevent an increase in total cases, the effective reproduction number (Re) — the number of new infections caused by one infectious person — for B.1.1.7 needs to be below 0.7, according to the modelling. Currently, Ontario’s Re is between 0.8 and 0.9.

If Ontario’s Re reaches 0.9, the group said, the variant is likely to trigger “exponential growth.”

Even if the provincewide case numbers are declining — as Ontario is seeing at the moment — “as the variant of concern spreads and becomes the dominant strain of the virus, you will see it actually start to drive up more cases because it is that much more transmissible,” said Steini Brown, co-chair of Ontario’s COVID-19 Science Advisory Table. “At some point, the old variant and the new variant curves cross and that starts to drive increase in cases.”

He added that this increase is likely to happen sometime in late February or early March.

The vast majority of the B.1.1.7 cases found in Ontario to date are outbreak-associated, most linked to the devastating COVID-19 outbreak at Roberta Place, a long-term-care home in Barrie, where all 129 residents were infected and 69 died.

Alarmingly, 28 cases of the B.1.1.7 variant detected so far (10 per cent) have no known epidemiological link.

Sharon Peacock is the executive director of the U.K.’s COVID-19 Genomics consortium, which monitors genome sequencing and analysis of the virus in that country. She told the BBC on Thursday that the B.1.1.7 variant, first detected last fall in southeast England, had “swept the country” and would likely “sweep the world.”

“Once we get on top of (the virus) or it mutates itself out of being virulent — causing disease — then we can stop worrying about it. But I think, looking in the future, we’re going to be doing this for years. We’re still going to be doing this 10 years down the line, in my view,” Peacock said.

Dr. Martha Fulford, associate professor in the Division of Infectious Diseases at McMaster University, said what is reassuring about the U.K.’s experience with the B.1.1.7 variant is that it does not appear to cause more severe illnesses than the previous variant and is transmitted the same way.

“Far and away, the single biggest risk factor for severe outcome is age — that hasn’t changed,” she said. “So the same measures that work for any respiratory borne infection of this sort continue to work,” such as staying home if you are sick, physically distancing and wearing masks in crowded situations.

She added that a big driver of transmission remains structural inequality, particularly in the hot-spot regions.

“We’re seeing transmission in certain areas where you have a lot of people living in close proximity, you have more people in precarious employment situations, you have a lot of people with no benefits,” she said. “Without fixing the inequities, the socio-economic issues that drive transmission, it really doesn’t matter which variant we’re talking about.”