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Parts of Ontario with the highest rate of COVID-19 cases aren’t testing as much as places with less spread
May 15, 2020
Patty Winsa

The regions of the province with the highest prevalence of COVID-19 cases are not testing as widely as ones with less spread of the disease, according to a study released this week by ICES.

Peel Region, Toronto and York Region, which are among the places where the virus is most prevalent, were in the middle of the pack when it came to per capita testing rates; they ranked 15th, 16th and 17th, respectively, in a list of 34 health units.

Ottawa, which has the third highest number of deaths in the province, ranked 26th.

The study by ICES (formerly the Institute for Clinical Evaluative Sciences), an independent, non-profit research organization, is the first to look at a number of factors related to testing in Ontario, including the per capita rate, which was difficult to gauge after the provincial government changed the way it reported the data last month.

Until then, the Ministry of Health had been publicly reporting the total number of patients tested for the virus, but it then changed its reports to show the number of samples tested per day. Because more than one sample is taken from some patients, this made it impossible to calculate a per capita rate. The ICES study looked at provincial data that was not publicly available.

“In places where there was less testing, we weren’t finding the cases, and, of course, transmission was happening under our noses without us realizing it,” said Dr. Camille Lemieux, an epidemiologist and the chief of family community medicine at the University Health Network. She is also medical director of UHN’s assessment centre for COVID-19 testing.

“When you have a new pathogen, when you don’t understand the epidemiology fully, the only way to understand it is to go looking for it,” says Lemieux, who was not involved in the study. “If you don’t look for it, you’re not going to find it and you’re not going to understand how transmission is happening.”

In comparison, the Sudbury region and other parts of northern Ontario had higher rates of per capita testing and low prevalence of the disease, the study found.

Part of the reason may be that testing was ramped up in those areas last month, when the north was given the go-ahead by the Public Health Ontario laboratory to test more widely, said Penny Sutcliffe, Sudbury’s medical officer of health.

“We had the green light ... in the north to do enhanced, or sentinel, surveillance,” said Sutcliffe, who explained that the public health lab -- which early in the pandemic produced all the province’s coronavirus test results, before other labs signed on -- then had some extra capacity.

Since April, “our bar has been pretty low as it relates to the symptoms for which a person could be tested,” said Sutcliffe. “It was really good that we were able to do that to get the sense of what’s happening in our communities and to get the message out about community transmission and what precautions we need to take.”

The study looked at testing data for the province from Jan. 15 to April 30.

Meanwhile, test restrictions at community assessment centres elsewhere in the province have been very narrow, despite the fact that, when the assessment centres were first created by the Ministry of Health, they were intended to provide public access, said Lemieux.

She said that shortly after the centres were created, the criteria for testing were limited quite dramatically, to some degree centrally but more through regional planning bodies created by the province to manage various aspects of the pandemic.

“Those initial criteria were really quite narrow,” said Lemieux. “(Tests) were limited to health-care workers; people working in high-risk environments, such as long-term-care homes, prisons, shelters and so on, and that really everybody else should not be tested , through the CAC (community assessment centres) mechanism.”

Lemieux says the criteria have remained strict, although in the middle of April there was a proviso in the guidelines that clinical discretion could be used. She said that in some cases UHN’s assessment centre has used this to avoid turning away people who didn’t fit the province’s criteria for testing.

“Up until this point in time, (the criteria) have sat there being very restrictive and not at all accomplishing the goal that needs to be done with testing,” she said. “And that’s to find, what does COVID mean in the community? How much is out there? Where are the hot spots? All of those important things that will define how we move forward.”

Although the Health Ministry sets testing criteria across the province, testing rates may differ among health units because of input at the local level.

Dr. Vinita Dubey, Toronto’s associate medical officer of health, said in an email that Toronto Public Health “uses the provincial testing guidelines and works with our local assessment centres to ensure they will test individuals who TPH deems are necessary to test for public health purposes. TPH works with long-term care homes, retirement homes, congregate settings and daycares to facilitate testing if required.”

Lemieux says she knows there have been problems with lab capacity and availability of swabs that may have limited the number of tests performed.

“But those hurdles are long behind us. The initial restrictiveness, which may have been grounded -- I’m not convinced of that -- but may have been grounded in some resource limitations , they did not mature in tandem with the availability of testing,” she said.