Yes, there's a decline in new COVID-19 cases. No, it's not enough to end Ontario lockdown, experts say

As Ontario approaches the end of its fourth week under a province-wide lockdown, epidemiologists say declining new infections prove the measures are working, but they warn we are still far from ready to reopen non-essential businesses, schools, and other heavily restricted activities.

Ontario reported 2,655 new COVID-19 cases on Wednesday. The seven-day average fell to 2,850, marking 10 consecutive days of decreases from a high of 3,555.

Ashleigh Tuite, an infectious disease epidemiologist at the University of Toronto's Dalla Lana School of Public Health, says the declining average is a "positive sign," but only part of the picture officials are looking at when considering the province's next steps.

'Small victories'

"I think it's important to look at those numbers and, you know, celebrate the small victories, but also recognize that we're going to be at this for a while longer," Tuite said in an interview.

On Wednesday, the province reported 1,598 COVID-19 patients in Ontario hospitals. 395 COVID-19 were admitted to intensive care units and 89 additional deaths were reported, matching a previous record.

Tuite and other experts say that those indicators remain far too high to consider easing lockdown measures. Getting to that point will require weeks, not days, of progress.

"What we want to see is that every week that goes on, there's a steady decline," Tuite said.

"I would say you probably want to see about a 25-per-cent decline week-over-week. When you see that trend, then you can start talking about opening things up again."

No magic number

Earlier this week, Ontario's Chief Medical Officer of Health Dr. David Williams said easing lockdown restrictions will require reducing new infections to "around or below" 1,000 per day. 

However, other infectious disease experts tell CBC News reopening won't be such a simple calculation.

"There's not necessarily a magic number in terms of number of cases," Tuite said.

Dr. Jeff Kwong, a senior scientist and infectious disease specialist at University of Toronto, says 1,000 cases per day is too high to consider lifting restrictions.

"I'm not sure where Dr. Williams got a thousand cases per day. I've heard we should be aiming for one [new daily infection] per million people. Ontario has a population of about 15 million people. So that would be 15 cases per day," Kwong said in an interview.

"Fifteen and 1,000 is quite a big difference.".

Williams also singled out reducing the number of  ICU admissions to 150 as another threshold for reopening. On Wednesday, Ontario reported 395 COVID-19 patients in the province's ICUs.

As for reopening schools, Kwong says it's a "really tricky call." Keeping them closed may help reduce the spread of COVID-19, but it's harmful to children. 

Kwong says more time is needed before returning to in-person learning, but in the meantime, he'd like to know what criteria the province is considering for reopening schools.

"We haven't identified any targets," he said.

Avoiding another lockdown

Even if infection, hospitalization and mortality rates can all be reduced to the point of reopening, is it just a matter of time until that very reopening causes them to shoot up again?

Pretty much, according to experts. But a vicious lockdown loop can be avoided with proper supports in place to test for, trace and isolate COVID-19 cases.

Tuite says rolling out more rapid testing will be key for a safe reopening, as well as ensuring employees have paid leave to stay home while they're sick.

Isolation hotels should also be maintained so COVID-19 patients won't infect other people at home.

"We have to do everything we can to ensure that once we get case numbers down, they stay down, and we have all of these other supports in place so that we can keep cases at a manageable level," Tuite said.