Wastewater data filling void as Canada’s PCR tests decline for COVID-19


While many Canadians continue to check daily case counts for COVID-19, some experts suggest that keeping tighter tabs on wastewater surveillance trends could paint a fuller picture, particularly as PCR testing becomes more and more limited.

The limited testing, now often reserved for high-risk and essential workers, is creating an underreporting of new virus cases that will only get larger as some jurisdictions, such as Ontario schools, suggest moving away entirely from reporting daily case counts.

While many health units in Canada’s urban areas already receive wastewater data, not as many are posting the new data online as public information. That may soon change, say officials with units such as Public Health Sudbury and Districts, as they look to fill the gap emerging from limited clinical tests.

“It does have the potential of being able to indicate trends where just given the provincial testing strategy at this time, may not be picking it up because of the numbers that are being involved,” Burgess Hawkins, manager of health protection at the health unit in Sudbury, told CBC News.

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As of August 2021, all 34 Ontario public health units had joined the $12 million province-wide Wastewater Surveillance Initiative, with approximately 160 sampling locations covering over 80% of Ontarians.

Sudbury health officials currently get wastewater data through a project involving the Health Sciences North Research Institute and Laurentian University. They said they are working on ways that make sense to provide wastewater data online to the public. They do want to remind citizens, however, that the wastewater data only essentially shows whether COVID-19 cases are on the verge of rising or declining, which may not satisfy some of the public’s more immediate thirst for finely detailed data.

Wastewater data in many regions is also revealing the quickly changing landscape from the Delta variant of COVID-19 to the Omicron variant becoming the primary signal.

“It’s unprecedented, this switch in the wastewater signal,” Tyson Graber, an associate research scientist at the Children’s Hospital of Eastern Ontario Research Institute (CHEO) told media about the emergence of Omicron in Ottawa’s wastewater over December 2021.

In Saskatchewan and parts of Ontario, for instance, the levels of the COVID-19 virus detected in wastewater has jumped nearly 90% since Omicron was first identified in December.


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