Public Heath officials opt for soft soap over science
Normality will not come back as before until a COVID vaccine has been developed, the prime minister has admitted.
With no cure on the immediate horizon, the news was as bleak as the April flurries that provided a backdrop to Justin Trudeau’s grim update on Thursday.
Statistics Canada reported that its March survey indicated one million jobs were lost, taking the unemployment rate to 7.8 per cent for the month. Even this underplayed the severity of the situation, given 5.47 million Canadians have applied for emergency assistance since March 15. The April jobs report will not be for the faint-hearted.
The Parliamentary Budget Officer added his harsh tidings, saying the federal deficit is set to reach $184 billion this year — 8.5 per cent of GDP — thanks, in part, to the $2,000-a-month emergency response benefit, which he estimated will cost $22.3 billion.
These were sombre numbers but were at least delivered in straight-up fashion, without ambiguity.
That was not the case with the federal government’s best guess on how the virus is likely to play out on the health front.
Public health modelling, like public opinion polling, should be used as a drunk uses a lamppost — for support, rather than illumination.
Scientists hate models, for the obvious reason that they have the potential to make them look like idiots in hindsight.
Horacio Arruda, Quebec’s public health director, said models predicting the course of COVID-19 would have as much scientific veracity as a horoscope — the day before releasing his department’s projection model at the behest of his premier.
Theresa Tam, Canada’s chief public health officer, clearly takes a similarly dim view of the astrology of virus prediction.
As she released her agency’s data Thursday, she warned the model is “imperfect” and “not a crystal ball.”
That reluctance was reflected in a report that was, at best, confusing, and at worst, misleading for anyone following along.
The Public Health Agency was bold enough to offer a straight-up prediction on how things might go in the next week — namely an increase in cases to around 27,215 from the current infection rate of 18,447, and a rise in the death count to between 500-700 from 401 on Wednesday.
After that, things got hazy. The agency offered a range of eventualities — suggesting a death toll of 11,000, if 2.5 per cent of the population is infected, or 22,000 if five per cent of Canadians become ill. These were cited as the best-case scenarios.
If “weak controls” are put in place — namely lax social distancing and a low percentage of cases and their contacts traced and isolated — the percentage infected could rise to 50 per cent and lead to an estimated 250,000 deaths over the course of the pandemic.
If no controls at all are put in place, the model suggested the infection rate could reach 80 per cent and result in up to 400,000 deaths.
I asked Tam where Canada is, or is likely to be, on that continuum. She was frank: “We don’t know.”
But the implication from the presentation deck was that, if we achieve the epidemic control scenario through isolation, travel bans and hand-washing, only a relatively small number of people will get sick and die. To put 11,000 deaths into context, in 2018, 8,511 Canadians died of influenza and pneumonia.
But that is not how the science works, as Tam and her colleagues know well. Isolation is working because people without immunity have not been exposed to the virus.
As Amir Attaran, professor in the faculty of law and school of epidemiology and public health at the University of Ottawa, pointed out, when social-distancing rules are relaxed, “as one day they must be,” viral transmission will resume.
The slide in the Public Health Agency deck that suggested strong interventions would keep infections to five per cent of the population was, in Attaran’s view “garbage.”
“They would not, unless (interventions) continued indefinitely until a vaccine is available, which no one expects in 2020,” he said.
The alternative to a vaccine is the development of herd immunity, which would kick in once between 40-70 per cent of the population have been infected. (The reproductive mode of the virus at that stage would fall to the point where each person infects fewer than one other person, and the epidemic dies out).
But for that to happen, somewhere close to half the population of this country has to catch COVID-19.
Extrapolating the Public Health Agency’s own figures, that would see 1.4 million people hospitalized, 460,000 patients entering intensive care units and nearly a quarter of a million Canadians dying.
The precise numbers may be as accurate as astrology but the epidemiology is not pseudo-science.
Which brings us back to the prime minister’s moment of uncommon frankness, when he suggested normal service will not be resumed until we have a vaccine.
“Social distancing and isolation buys us time before reaching that destination but it is incapable of changing the destination,” said Attaran.
The Public Health Agency did not tell that story, preferring soft-soap to science and the straight goods.