Variant could cause major spike in cases, model shows,
Modelling shows that Ontario reopening could lead to 9.8K cases a day
New cases of COVID could rise to more than 9,800 a day by April if the variant from the United Kingdom takes hold in Ontario, according to modelling based on the provincial government’s staggered reopening plan.
The projections show that even if the province delays the reopening of health units, from the planned six days to three weeks, once Toronto, Peel and York reopen cases will take off, a trend that is due in part to high case counts in the GTA and the presence of the highly transmissible B.1.1.7 variant, which is expected to overtake all other strains.
The data suggests that “if you want to keep the numbers low, then you then you have to delay the reopening of those hot spots,” said Chris Bauch, a professor and a university research chair in the Department of Applied Mathematics at the University of Waterloo.
The model shows a spike in cases that is very similar to what has happened in countries with the B.1.1.7 variant, including the U.K. and Ireland, where cases ramped up quickly.
“I think throughout the epidemic, there is this repeated failure to appreciate these rapid spikes and how they can materialize,” said Bauch. “So I think decision makers are thinking, well, right now everything looks great and so let’s reopen. They’re not thinking, three weeks, six weeks ahead.”
The model is based on the plan announced by the government earlier this week to reopen health units in groups, the first three on Feb. 10, followed by another 28 on Feb. 16 and finally Peel, York and Toronto on Feb. 22.
On Friday, the province announced it would delay reopening the North Bay Parry Sound District Health Unit until Feb. 22 after a request from the area’s medical officer of health, Dr. Jim Chirico, who was concerned about variant cases.
Bauch created the models with post-doctoral fellow Kathyrn Fair and professor Anand Madhur, both in the School of Environmental Sciences at the University of Guelph.
The model doesn’t account for the vaccine rollout, which could have an impact on case counts, especially if the staggered lockdown by regions was delayed a couple of weeks.
If we “lengthen the gaps between the reopenings to three weeks instead of six days, that does at least kind of push us back in terms of where cases start coming up,” said Fair. “And that combined with the fact that hopefully the vaccine rollout will be occurring, would be something that would create a more manageable situation.”
More vaccinations could also mean fewer deaths in the third wave.
“The thing to keep in mind about these projections, is that these are projections of cases,” said Bauch. “So if we’re vaccinating the most vulnerable Canadians, where the death rates are sky high, then the death rate will drop. And what we won’t see is deaths increase as much as cases.”
The B.1.1.7 variant is expected to become the dominant strain of the virus here by mid-March, said Bauch. The model shows that if the variant wasn’t in circulation, reopening would cause a third wave that was very similar to the second.
“If there wasn’t the new variant, things would have been more or less OK to proceed in the way that they’re proceeding,” said Anand.
The model also shows that if we had continued with the latest lockdown, cases would have increased slightly, not only because of the variant but because of our behaviour over time.
“Basically if you keep running the simulations for long enough, the extent to which people will distance lessens because people are fatigued (due to the lockdown) and there are costs associated with doing it of course,” said Fair.
Each projection shown in the model is a mean of 30 simulations that are based on previous data from the pandemic as well as parameters such as transmission and testing rates.
Dionne Aleman, a University of Toronto professor and expert in pandemic modelling, said the data shows that it’s still too early to say when Toronto, or even the GTA, should reopen.
“There’s definitely reason for hope,” said Aleman, who wasn’t part of the modelling team. “We are trending very quickly down. But it will probably be another month, maybe two, before things get low enough where our major metropolitan centres can really safely start to reopen.”