Forecasts for second wave of COVID-19 in Ontario to peak in October


New projections suggest that the second wave of COVID-19 in Ontario will peak between mid to late October and likely send enough intensive care patients hospitals need to cut back on elective surgeries.The predictions come from the COVID-19 Modeling Collaborative, a joint effort of scientists and doctors from the University of Toronto, the University Health Network, and Sunnybrook Hospital.

Given how quickly Ontario’s infection rate has increased in recent weeks, the model predicts the province is on track to surpass 1,000 new cases per day by mid-October , unless stricter public health measures slow the acceleration of the spread.

The average number of new cases reported daily in Ontario is now four times higher than it was at the end of August. Premier Doug Ford’s government has since reduced size limits for private gatherings, reduced bar opening hours and ordered strip clubs closed.

On Sunday, the Ontario Ministry of Health reported 112 hospital patients with a confirmed case of COVID-19, nearly triple the number from two weeks ago. The research team says the impact of the second wave on Ontario hospitals will depend on the demographics of those infected in the coming weeks.

The dotted line shows the current forecast for the onset of the second wave of COVID-19 in Ontario, based on the work of a team of researchers at the University of Toronto, University Health Network and Sunnybrook Hospital. The solid lines model the evolution of the number of cases if the second wave follows the patterns observed in Ontario in spring (orange), in Michigan this summer (light gray), in the Australian state of Victoria (dark gray) or in Italy in the first wave of the pandemic (black). (COVID-19 ModCollab)

“We are at this critical moment when the number of cases is increasing and we are not yet sure where it is going,” said Beate Sander, scientist at the University Health Network and holder of the Canada Research Chair in the economics of disease. infectious.

“Right now we have mostly younger, healthy people (contracting COVID-19 in Ontario),” Sander said in an interview with CBC News. “But what we’ve seen in other jurisdictions is that it’s really spilling over to other population groups. ”

The team of researchers developed four scenarios of how Ontario’s second wave might unfold from here.

The best-case scenario would mimic Ontario’s first wave in March and April, when the number of cases rose rapidly but was subsequently held back by a lockdown.

Two moderate scenarios would look like how a second wave hit jurisdictions comparable to Ontario: the Australian state of Victoria (home to Melbourne, a city of 5 million people) and the US state of Michigan.

Long lines at testing centers, like this one pictured in Toronto on September 21, 2020, reflect a spike in COVID-19 cases from provincial health officials linked to people under 40 not following not public health guidelines at social gatherings. (Evan Mitsui / CBC)

None of these three scenarios show that patients with COVID-19 are filling Ontario’s hospital wards or intensive care units beyond their capacity. This only happens in the modelers’ worst-case scenario: a second wave as bad as the first wave that hit Italy when the pandemic began.

However, in all but the best-case scenarios, researchers predict a demand for intensive care that exceeds the capacity required for patients undergoing scheduled surgeries.

“Very high risk cancer surgeries, for example, will not be able to proceed if ICUs are overwhelmed with people presenting to the emergency room dying from pneumonia and respiratory failure associated with COVID-19.” said Dr. Kali Barrett, an intensive care physician at the University Health Network and a member of the modeling research team.

The researchers stress that their modeling scenarios are only predictions. They use data on the proportion of people who ended up in hospital and intensive care units while positive for the coronavirus, and project it onto Ontario’s current trend in new cases.

The changing demographics of those infected with COVID-19 as the second wave develops, makes it difficult for researchers to predict the number of people who will need hospital treatment.

“The second wave in Spain and France started in younger populations, but it is spreading to older people and people at greater risk of ending up in intensive care units or hospitals,” Barrett said in an interview. at CBC. News.

“It is only a matter of time before this virus, if it affects young populations, spreads into the elderly population,” she said. “We’re already starting to see this happening in Ontario. ”

The latest figures from the province’s health ministry show 227 people aged 70 or older have a confirmed case of COVID-19. This number increased by 34% in the space of a week.

Changes in the eligibility criteria for testing can also cloud forecasts. When testing is widespread and captures a larger number of mild cases, the percentage of those who end up in hospital will be smaller than when testing is limited to priority groups most likely to be infected with the virus, such as this was the case in Ontario in the spring.

Ontario changed its “anyone can take a test” policy on Friday, so far fewer people without symptoms are now eligible for the test.

Demand for intensive care could lengthen the surgical backlog

Ontario has approximately 2,000 intensive care beds and the province plans to add 139 in October. The province’s intensive care beds are typically two-thirds occupied by patients whose cases have nothing to do with COVID-19, whether it’s a heart attack, a car accident or other serious illness.

Since intensive care units cannot operate 100% full time, researchers calculate that Ontario has about 475 beds available for elective surgery patients and patients with COVID. When the planned surgeries are going at full speed, these patients occupy all of these beds except 100.

This graph predicts what will happen in Ontario if the second wave looks like what happened in the Australian state of Victoria, home to the city of Melbourne. It would see some 1,200 patients in general hospital wards across Ontario and between 350 and 400 patients in intensive care beds (ICUs) at the peak in late October. (COVID-19 ModCollab)

Their conclusion: If more than 100 people with COVID-19 need intensive care, they would be competing for space with cases of scheduled surgery.

“Then we’ll have to make decisions about who to treat,” Sander said. “Are we admitting COVID patients or doing (elective) surgery?” ”

Projections suggest that if Ontario’s second wave follows what happened in the Australian state of Victoria – a sharp rise in new infections that decline rapidly after a strict lockdown – some 350 to 400 people will need an intensive care bed in case of peak demand at the end of October.

If the second wave in this province plays out like that of Michigan – an increase in new infections that stabilizes but does not slow down for a long time – the forecast is for more than 200 patients with COVID-19 in ICUs starting in late October From.

Figures released by the Ministry of Health on Sunday show 28 intensive care patients with a confirmed case of COVID-19.

In Ontario’s first wave, the number of COVID-19 ICU patients peaked at 264, while the number of people hospitalized at any one time peaked at 1,043. Elective surgeries have been postponed in the whole province.

While the majority of Ontario’s second wave infections are in younger, healthier people – as happened through September – hospitalization rates are expected to be lower than in the spring.

The modelers say that the number of intensive care unit occupancies will be more of a concern than the total number of hospitalizations, because the Ontario hospital system can free up general ward beds much more easily than it can do. the place in intensive care.

It is less about the beds and ventilators available, and more about having enough doctors and nurses who can provide the specialist care that critical care patients need.

“You can just train people overnight to do this stuff,” Sander said. “You can buy a lot of beds and you can buy a lot of ventilators, but you can’t get these highly trained people in the field in a very short period of time. ”

Barrett acknowledges that human resources are the main limiting factor and is concerned about how the second wave might affect hospital staff and their families.

“The majority of people working in hospitals are 30, 40 and 50 years old, so a lot of them have children who go to school,” she says. “If there is a massive epidemic among the younger population and schoolchildren, a whole sector of our health workforce will not be able to come to work.


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