COVID-19 case numbers don't tell the whole story of the pandemic, experts say

As the number of new daily COVID-19 cases continues to rise in some provinces, experts say that is not the only metric important when it comes to monitoring the pandemic.

Dr. Isaac Bogoch, an infectious diseases faculty member at the University of Toronto said we need a “lot of metrics to really frame how this pandemic is going.”

He told CTV’s Your Morning on Thursday that monitoring hospitalizations and hospital capacity is “extremely important.”

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“We definitely need to focus on that, including here in Canada, where we actually have pretty limited ICU capacity,” he said.

But Bogoch said we shouldn’t “completely ignore case numbers.”

“Case numbers are one of several metrics – we look at case numbers, we look at the seven-day average, we look at the per-cent positivity of tests, we look at the hospital capacity, we look at the number of people in hospitals, ICU deaths, we look at the R value – which is ‘is the pandemic growing or shrinking?’”

He said there is “no one metric that tells the whole story.”

“We don’t want to overemphasize or underemphasize any metric,” he said. “We just want to look at all of them and put them in the appropriate context to get a better picture of what’s actually happening.”

REACTIVE VS. PROACTIVE PANDEMIC RESPONSE

Dr. Jennifer Kwan echoed Bogoch’s remarks, saying there are several metrics that researchers and physicians monitor in order to better understand what’s happening with the pandemic.

“I always say that all metrics are important, because they all tell us different parts of the story, different perspectives,” she told CTVNews.ca in a telephone interview on Friday.

Kwan has been providing updates on the COVID-19 situation in Ontario on Twitter every weekday.

She said case numbers are important, though, because they are “an early warning sign.”

“When we wait for things like hospitalization numbers, ICU numbers and death numbers to rise, that takes some time,” she said. “It takes time to get sick enough to be hospitalized and pass away.”

“And if we are only reacting to rises in hospitalizations and deaths, it’s already too late enact measures to prevent that from happening in the first place,” she continued.

Kwan said that if we wait to make adjustments to our COVID-19 strategy based on changes to the hospitalization or death rates, the country would be taking a “reactive, rather than proactive approach.”

Beyond case counts, Kwan said that as a family physician she’s particularly interested in hospitalization and intensive care unit (ICU) numbers.

“Because it can affect the capacity of the health-care system,” she said. “In the past when ICU beds were full, it affected other parts of care, including people who were scheduled to undergo life-changing or life-saving surgical procedures, and sometimes that had to be postponed if there was no available beds for them.”

Ultimately, though, Kwan said she “learns a lot from all the numbers.”

“For example, test per-cent positivity also seems to sometimes rise before case counts,” she said. “So it’s kind of an even earlier warning sign.”

What’s more, Kwan said, COVID-19 related deaths have been a “more accurate metric” than case counts throughout the pandemic.

She said that during the first wave of the pandemic there weren’t enough tests, meaning it’s likely not all cases of COVID-19 were detected.

“And throughout the pandemic the requirements or the recommendations for testing in terms of symptoms would change,” she said.

Kwan said that when someone passes away from COVID-19, it provides a “more clear, consistent metric” which helps researchers understand the severity of the wave.

BUT NUMBERS ARE NOT THE WHOLE STORY

Dr. Sumon Chakrabarti is an infectious diseases specialist with Trillium Health Partners in Mississauga, Ont.

He told CTVNews.ca that while monitoring metrics like case numbers and hospitalizations are important because they can “give us an idea of what’s going on,” they can’t capture the whole picture of the pandemic.

“There’s not one good metric, or two good metrics that you can look at that can tell you the whole story,” he said. “You kind of have to know what’s happening in each situation [across] the country.”

He pointed to the Greater Toronto Area (GTA) as an example.

“Part of the reason why the GTA got hit so hard is that -- number one -- we have a huge population, but we also have our manufacturing sector here,” he explained. “So all these high-density workplaces all in one geographic area, being worked at by people who themselves live in really crowded homes.”

He said other places, like the East Coast of Canada didn’t have the same problem, and therefore weren’t hit as hard.

The numbers, Chakrabarti argues, can’t accurately capture all of these nuances.

“People always look at the numbers, but I just think it's important to realize that these numbers have been ruling our lives for the past two years,” he said. “It sucks, because everybody makes every decision based on them, and they’re just very imprecise.”

He said his “main message” is that you “have to know the context” to understand what’s happening with the pandemic.

“And that’s not often encapsulated by just the numbers,” he said.

WHAT ARE THE NUMBERS?

The latest data released on Friday by the federal government suggests that while cases are increasing in areas across the country, other metrics like hospitalizations have decreased slightly.

The numbers show between Nov. 29 and Dec. 6, the number of hospital beds occupied by COVID-19 patients dropped from 1,164 to 1,116.

The number of beds in ICUs occupied by COVID-19 patients also decreased from 470 to 445.