Via The New York Times, a report from Canada: Coronavirus Models Offer the Big Picture, Not the Details of What May Come. Excerpt:
Ontario followed British Columbia on Friday by releasing its projections for what may lie ahead in those provinces with the coronavirus.
But before getting into that, here’s some advice about those forecasts from Dr. Ross E.G. Upshur, a physician and researcher who is the head of clinical public health at the University of Toronto’s Dalla Lana Faculty of Public Health: “Don’t obsess about the numbers because they will change.”
Dr. Upshur isn’t dismissing the forecasts. He said that they were an important planning tool for the health care system. “All models lie,” he said, citing a popular expression in his professional world. “But some are more useful than others.”
He compared the forecasts from the provinces to the ones Environment Canada issues for the weather. Both start with a set of assumptions, which are constantly refined, and each piece of data that’s fed into them subtly affects their predictions. Canadian researchers, Dr. Upshur said, have already adjusted their assumptions to reflect that victims here have, on the whole, been older and were afflicted with more medical conditions before becoming infected than people killed by the virus in China.
The result, he said, is much like the view people with myopia have when they remove their glasses. They can see the general outline of things but “it’s not going to be clear and in detail.”
Complicating things is that Ontario and British Columbia released numbers that largely looked at different factors. Both offered a mix of grim news and mild encouragement.
British Columbia focused on the number of cases, people expected to test positive for the virus, while Ontario’s emphasis was on the likely number of deaths.
The British Columbia model suggests that the steps taken there have been effective at slowing the rate of growth of cases. And signs are looking positive that its medical system won’t be overwhelmed by people who develop severe illness from the virus.
As Premier Doug Ford warned in advance, Ontario’s model made for grim reading. It currently estimates that by the time the virus has run its full course, perhaps 18 months to two years in the future, it will have killed 3,000 to 15,000 people in the country’s most populous province. But in the absence of preventive measures including the current shutdown of most aspects of daily life, the model projected 100,000 deaths related to the virus.
On Friday, Mr. Ford also expanded the scale of that shutdown.
“We’ve told the vast majority of Ontario’s work force to stay home,” he told a news conference. “Lives are on the line.”
Ontario’s forecast for the number proved difficult to calculate because of a large test laboratory backlog, which has just been cleared. But Dr. Peter Donnelly, head of Public Health Ontario, said that its track, the rate at which cases are growing, was closer to that of the United States rather than British Columbia.
Despite this, Ontario is projecting that its hospitals, like those in British Columbia, are not likely to be overwhelmed after including current plans to expand their acute care capacity. But the province's PowerPoint charts show that’s the case just by a whisker.
Dr. Upshur said that the two provinces’ models suggested they were behind China and Italy at this point. That, he cautioned, does not mean that things are good.
“Covid-19 is very, very worrying and dangerous indeed,” he said. “This may be the biggest single challenge since World War II.”
All week, Prime Minister Justin Trudeau has been pressed to release the federal government’s forecasts. But its models are built on data from the provinces. On Friday he again promised that they would be made available, but said that the government was still waiting for figures from some provinces.
