Federal modelling shows epidemic growth slowing
Long-term care home outbreaks responsible for majority of deaths
Outbreaks of COVID-19 in long-term care and seniors’ homes in Quebec, Ontario and Nova Scotia are responsible for 79 per cent of COVID-19 deaths countrywide.
This startling new figure was released Tuesday as part of updated federal modelling. This is the first update to the initial modelling figures released April 9.
“Outbreaks in high-risk populations are the driving force behind the regional epidemics, in particular outbreaks in long-term care and seniors’ homes are driving epidemic growth in Quebec, Ontario and Nova Scotia, and are responsible for the majority of all deaths in Canada,” said Chief Public Health Officer Dr. Theresa Tam.
According to the figures, health officials expect 53,196 to 66,835 cases and 3,277 to 3,883 deaths by May 5. As of Tuesday afternoon, there have been 49,025 confirmed cases and 2,766 deaths in Canada.
Modelling released on April 9 underestimated the number of deaths that would occur, predicting only 500 to 700 by April 16.
Tam said this is because of the changing epidemiology, mainly due to the outbreaks in high-risk settings.
“Right now we are seeing the tragic paradox of the epidemic playing out as the epidemic comes under control and the growth of cases slows, the severe outcomes and deaths continue to accrue as COVID-19 takes a heavy toll among highly susceptible populations,” she said.
Tam said the models have been adjusted for the higher case fatality rate, and changes will continue to be made to forecasting models based on real data.
The available data also shows clear trends in the way the coronavirus is affecting different segments of the population. For example, individuals over the age of 60 make up 95 per cent of deaths, 66 per cent of hospital admissions and 63 per cent of ICU admissions. Males are also more likely to be admitted to hospital (20 per cent versus 14 per cent) and twice as likely to be admitted to ICU (six per cent versus three per cent).
In Canada, 5.5 per cent of those infected have died, 17.1 per cent have been admitted to hospital and 4.2 per cent have been admitted to ICU.
Tam said it is expected the case fatality ratio will continue to change over time.
Though 75 per cent of hospitalized cases are people with one or more underlying health condition, no one is immune to severe outcomes of the coronavirus, Tam said.
PROVINCIAL DIFFERENCES
The rate of growth varies significantly across the provinces. Some provinces, such as New Brunswick, Newfoundland and Labrador, and Manitoba, have managed to almost entirely flatten their first wave — as of Tuesday, New Brunswick had not seen a new case in 10 days — whereas others, such as Ontario, Quebec and Alberta, are still seeing significant growth in the number of cases.
There is no community transmission occurring in Prince Edward Island, the Northwest Territories or the Yukon.
The two largest provinces, Ontario and Quebec, represent more than 80 per cent of confirmed cases, Tam said, while B.C. and Alberta are the next most affected provinces, accounting for 14 per cent of cases.
Elsewhere, case counts are lower, but all provinces and territories except Nunavut have reported cases.
“The epidemiology of COVID-19 is not the same in all parts of the country, so when and how control measures are readjusted and relaxed will need to be decided based on the local epidemiological situation,” Tam said.
THE GOOD NEWS
The modelling related Tuesday paints a picture of a Canada that is on the right track, but still has a long way to go,
One of the positive takeaways is that Canada’s epidemic growth is slower than many other countries, though growth is declining across most comparison countries due to strong public health and global measures.
Canada’s epidemic growth has also slowed significantly: at the outset, cases were doubling every three days; as of April 15, cases were doubling every 10 days; and as of Tuesday, the number of cases in Canada was doubling every 16 days.
“Canada's epidemic is bending as the rate of growth slows down in response to our collective control efforts,” Tam said
Overall, Canada is working with different modelling scenarios, but Tam said the one officials are working toward is a scenario with stronger epidemic controls, which includes a high degree of physical distancing and a high per centage of cases and their contacts traced and isolated or quarantined.
This would result in a one per cent to 10 per cent infection rate, and the curve peaking earlier and beginning to flatten by mid to late summer, Tam said.
Weaker controls would result in an infection rate of 25 per cent to 50 per cent, and with no controls the infection rate would be 70 per cent to 80 per cent, she said.
By achieving epidemic control, only a small proportion of the population will be immune, Tam said.
“Until the population has developed a high level of immunity to the virus or we have a vaccine in place, we have to plan to live with a manageable level of COVID19 activity,” she said.
Therefore, Tam said, officials anticipate that some public health measures will need to remain in place for some time to prevent the sparking and growth of future epidemic waves.
“We are making clear progress to slow the spread and bring the epidemic under control thanks to the commitment of Canadians who are following public health advice to protect themselves and others,” Tam said.
“It is critically important that we maintain our public health measures until we have achieved epidemic control, as relaxing controls too quickly will squander our collective efforts to date.”