Ontario's case numbers 'don't reflect reality' of who has COVID, virus expert says

The incidence of the virus found through wastewater testing is likely a better indicator, a Western research chair says.

Incidence of the virus found through wastewater testing is likely a better indicator, research chair says

"They don't reflect reality in any way right now," says Dr. Eric Arts of Ontario's daily COVID case numbers. He suggests using wastewater tests to estimate instead. (Liny Lamberink/CBC)

The number of new COVID-19 cases in Ontario is likely at least three times higher than what the province reports every day, says one expert in viral control. 

And that daily number, he says, may no longer be the most accurate way to track the spread of the virus.

Dr. Eric Arts, Canada Research Chair in viral control at Western University, says wastewater testing is a fairly accurate reflection of COVID-19 rates.

The daily numbers are still necessary to predict the rise in hospitalizations, Arts says. But since the province has reserved PCR testing for symptomatic people in high-risk settings, the numbers don't show the real picture. 

"They don't reflect reality in any way right now, partly because the vast majority of people are not being tested that have symptoms and in all likelihood have SARS-CoV-2 or Omicron," said Arts.

"As we start seeing changes in those testing numbers and hospitalization numbers, we'll have a sense of how the pandemic is evolving in the community," says Dr. Rabia Bana, Waterloo region's associate medical officer of health. (Region of Waterloo/YouTube)

Ontario health units say they're also looking to other numbers to get an accurate reflection of COVID rates. In Hamilton, Dr. Elizabeth Richardson, medical officer of health, says wastewater testing hasn't really worked.

"We're betting it has something to do with our system — the way it's set up when it comes to overall wastewater management," she said.

Dr. Rabia Bana, Waterloo region's associate medical officer of health, said last week that local testing has a positivity rate as high as 40 per cent. That and wastewater monitoring give "a comprehensive picture."

"We know that we have very high levels of community transmission in our community, and locally here in the region," she told reporters.

Dr. Elizabeth Richardson, Hamilton's medical officer of health, says wastewater testing hasn't been a good indicator in Hamilton. (Bobby Hristova/CBC)

"So I think we know and can expect that over the next six to eight weeks, we are going to see a rise in the number of cases."

Arts talked to CBC News Tuesday about the new reality of COVID numbers. The following has been edited for length.

How inaccurate are the daily numbers that the province is putting out every day at this point? 

Very. They don't reflect reality in any way right now, partly because the vast majority of people are not being tested that have symptoms and in all likelihood have SARS-CoV-2 or Omicron. 

Is there a reason to be reporting the daily numbers then if they're not even close to accurate? 

Yes. The reason why is we need to understand when we reach our peak and how long that lasts, and when the wave of hospitalizations will emerge and when it will end. That has been a pretty significant number through the past waves. So without understanding where we are with case counts, we don't know how our hospitalizations will change over time. And we don't know if the mitigations that, for example, the Ontario government just put into place are having an effect.

Are we able to even ballpark what the real numbers are at this point?

We definitely can do that. The way we've been doing it over over a year now is monitoring the wastewater in most major urban centres across Ontario through a program that's run through the Ministry of Environment in association with the Ministry of Health. That data is accumulated and analyzed. Basically, the idea is that most people that are infected with SARS-CoV-2 also defecated into the water.

Then we monitor the water and wastewater plants across the province. There are a number of laboratories, including ones in Waterloo and Guelph and at Western that do a pretty heavy load of analyzing and reporting that back to the Public Health Ontario and the Public Health Agency of Canada. That is utilized in estimating the numbers of cases in the province and in the country. 

Is the government looking at that kind of metric to guide its policy?

Well, I'm not at the level where I can say that. I know that we report the data here in London from multiple sites in Ontario, and there are others that do it across Ontario. That all goes into a central database that is then compiled and provided to the province.

In past waves, it tracked very well with case counts. In this current wave, we could use that as an estimate of the number of cases and the burden that we have. In all likelihood, we estimate that we're about three times off the reporting of cases in terms of the total number of cases.

So we're closer to, maybe, 50,000 new cases a day?

Potentially. And it's really hard because I don't have access to all the numbers, for example, on the wastewater across Ontario, and I don't have access to the modellers that would estimate the number of cases across Ontario. But that can be done, and I suspect it is being done for the province. It's just not shared publicly. 

Chief Medical Officer of Health Dr. Kieran Moore mentioned using hospital data, but we know that comes after the fact, when people are already sick enough to be hospitalized. How do we know when we're heading in the direction of hospitals being full?

Well, that's where this information comes in. For example, wastewater is probably the way we have to track it now because we're not getting accurate information on case counts. If we look at it, it looks like the case counts are actually going down, not up. But we also know that there's insufficient testing in the community, so we need a different metric to measure case counts now. Unfortunately, I think wastewater is about the only one we have.

I don't think we've hit our peak yet in the number of cases, so we probably have not hit our peak at the number of hospitalizations.


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