The high number of COVID-19 cases in long-term care homes could be what propelled Canada’s death toll significantly higher than what officials predicted just last week, according to the country’s top doctor.
The models are not meant to be exact but serve to inform decision-makers and help them plan during the pandemic. However, the much-higher number of deaths is raising more questions about the underlying assumptions federal scientists are using in the modelling and why those assumptions are being kept in a “black box” rather than shared publicly, according to one expert.
Models released by the federal public-health agency on April 9 predicted the upper limit of novel coronavirus-related deaths in Canada by April 16 would be 700. Instead, 1,195 people had died as of Thursday evening. Conversely, the number of confirmed cases in Canada (30,106) falls within the 22,580 and 31,850 predicted by the models for the past week.
The high proportion of cases in long-term care facilities “unfortunately results in higher fatality amongst the people who get ill,” Chief Public Health Officer Theresa Tam said Thursday.
Dr. Tam also cautioned that “at the beginning of any epidemic, the case fatality [rate] will be underestimated" because of the time it takes for the illness to take its course. But she didn’t directly answer whether this means that the total number of deaths at the end of the pandemic is also likely to be higher.
To understand what’s going on with the models, and why there have been so many more deaths in the one-week span, Zulfiqar Bhutta, director of research at the Centre for Global Child Health at the Hospital for Sick Children in Toronto, said much more information about the models needs to be made public. For example, he said it’s important to know the proportion of deaths in long-term care that fall into the bracket of unexpected deaths.
“There could be a simple explanation for this, and there could also be an explanation that their estimations of the translation of number of cases, to hospitalizations, to deaths is off,” Dr. Bhutta said.
The population age distribution that the models rely on is one example of an assumption that influences the models, but that hasn’t been released, Dr. Bhutta said. That data gap makes it difficult to verify the federal government’s models or recommend areas where they need to be recalibrated.
Ottawa’s approach is different from governments in the United States and Britain, which have relied on the “full force" of academia to help inform their pandemic projections, he said. “I just don’t understand why this would be kept under wraps."
With almost 500 deaths above what was predicted in one week, Prime Minister Justin Trudeau on Thursday underscored that the models are “not a declaration of what is going to happen,” but allow officials to prepare for the short and long term.
He said the deaths in long-term care show “we need to take more measures to protect our seniors” and that he would raise it with the premiers in their weekly teleconference.
Because Canada is still in the early days of the pandemic, Dr. Bhutta said more data over the next few days will help to show whether the models are holding up or need changing.
By Tuesday, Dr. Tam said the latest federal estimates show that between 1,200 and 1,620 people could die as a result of the disease. But she again cautioned that those projections are subject to change.
Sign up for the Coronavirus Update newsletter to read the day’s essential coronavirus news, features and explainers written by Globe reporters.