Modelling shows what could happen if Ontario relaxes physical distancing too quickly
TORONTO -- If physical distancing measures in Ontario are relaxed too much without improved efforts to limit the spread of COVID-19, the virus could rapidly overwhelm intensive-care units beyond their capacity, according to new modelling data.
“What starts to happen is you don’t have enough ventilators for everyone,” Dr. David Fisman, a professor of epidemiology at the University of Toronto who published an article with his colleagues Wednesday in the Annals of Internal Medicine, told CTVNews.ca via telephone Wednesday night.
“So you have to start triaging and deciding who is worth trying to save and who you’re going to give up on … that’s why this is such a big deal.”
The researchers used infectious disease modelling to study the potential impact of physical distancing in the province. They found that when the number of contacts between people increased to more than 50 per cent of normal levels, disease activity spiked.
Such a resurgence would push Ontario hospitals beyond the number of patients they are capable of handling and cause “substantially higher mortality,” as was the case in overloaded hospitals in Italy, Spain and New York City.
“Relaxation of physical distancing measures without compensatory increases in case detection, isolation, and contact tracing was projected to result in a resurgence of disease activity,” the researchers wrote.
The researchers suggest that, without improved capacity for testing and contact tracing, policymakers in Ontario should consider staged relaxation of physical distancing while also closely monitoring the numbers.
Health officials say limiting contacts remains an essential way to fight the pandemic and flatten the curve. Fisman compared the number of contacts a person sees to a dimmer switch for a light.
"As you dim down the number of contacts, you should be able to get that reproduction number low,” he said.
But the dimmer also goes the other way. The modelling suggests that a return to normal levels of contact would “rapidly results in cases exceeding ICU capacity,” the researchers wrote.
Earlier in the pandemic, the researchers used the same modelling to determine that early physical distancing measures effectively mitigated the spread of the virus. Without this intervention, the researchers projected that Ontario would have quickly surpassed its ICU capacity and faced “substantially” more deaths.
Fisman admitted that he is worried about the situation in Ontario.
“Things have been moving in the wrong direction,” he said. “We haven’t sealed the deal. Most other provinces have been able to bring things down, lower cases day by day, and eventually look towards reopening that way, and Ontario hasn’t quite gotten it together.”
LARGE VS. SMALL GATHERINGS
Thirty per cent of Canada’s 87,519 COVID-19 cases are in Ontario, which continues to report hundreds of new cases per day. Quebec leads the country with 56 per cent of all cases, while provinces like B.C. have seen daily cases drop to single digits.
Ontario Premier Doug Ford has gradually relaxed restrictions in the province. A long list of businesses have been allowed to reopen, including most retails stores with a street entrance, as long as they follow a number of rules including physical distancing.
The province has previously suggested that it was considering increasing the size of permitted social gatherings beyond five people, but due to a rise in cases, the directive was pushed back.
When it comes to the impact of expanding social gatherings, Fisman highlighted the difference between large and small gatherings.
“We know enough about very large gatherings to be very wary until we have a vaccine,” he said, citing examples such as festivals and street parties. "I think the mass gathering that is hardest for society to cancel is schools, so there will hopefully be some studies in epidemiology in kids this summer.”
He added: “With smaller gatherings, I don’t think anyone yet knows what the tipping point is.”
Last weekend, an estimated 10,000 people broke physical distancing guidelines by gathering in Toronto’s Trinity Bellwoods Park. One bioethicist suggested that “isolation fatigue” — a psychologically-based restlessness that makes people want to break distancing rules — could be partly to blame.
Fisman acknowledged that it’s difficult to limit your social contacts. But those sorts of gatherings can cost lives.
“I don’t think the people in Trinity Bellwoods are going to get sick, because they’re young people, but that’s not the point. This percolates through our community and does hit people who are older and vulnerable,” he said.
For example, on Wednesday morning, Fisman woke up to a text message from a friend who works as an infectious disease doctor: “I had another patient die today. A mother in her 60s. The whole family got COVID. This is madness.”
“Just because it’s not affecting your family right now doesn’t mean its not affecting someone else’s,” Fisman said.
With files from CTV News Toronto