Crucial data from wastewater research projects designed to provide early tracking for COVID-19 has been provided to Toronto Public Health (TPH) since last summer. But as a third wave hits the city, there are no indications the information is being used to shape the way the city is dealing with the pandemic.
“We have received pilot data from the academic laboratories who are leading the testing,” Toronto’s Associate Medical Officer, Dr. Vinita Dubay said in a statement to CityNews. “We continue work to analyze this information.”
Ryerson University’s Urban Water Research Centre has been collecting samples from all four of the city’s water treatment plants, as well as other sites in Toronto. The samples are brought to labs where genetic material from the virus can be extracted, to help determine overall COVID-19 levels.
“Wastewater surveillance can pick up changes in the trends sooner than the clinical testing will. So there’s potential there that it’s a bit of an early warning system,” researcher Claire Oswald said. “That’s the goal of all of this: to provide them the information and have discussions around how to interpret that information and help them to decide if it’s helpful for their decision-making around social or medical interventions.”
Between July and October last year, Ryerson developed their program with assistance from the city and provincial governments. It has since increased the number of testing sites and frequency of sampling.
Other universities have also taken on similar research and are collaborating in a province-wide initiative.
The University of Ottawa’s faculty of engineering and the Children’s Hospital of Eastern Ontario (CHEO) Research Institute are working on COVID-19 wastewater research daily and provide same-day results to public health officials. That information is available to Ottawa residents through Ottawa Public Health (OPH) and a dedicated website.
“This is an additional measure that is taken into account by public health units,” CHEO cell biologist Tyson Graber said. “Together with the clinical picture, either clinical cases that are happening in that community and the hospitalization data, all those three kinds of measures are taken into account.”
Both Graber and OPH officials say that while the process of interpreting test results is still in its early stages, they can now compare the number of positive tests with wastewater data.
“Over the last three months, sharp increases in wastewater virus detection have almost always preceded an eventual surge in lab-confirmed cases and increased community transmission and outbreaks,” OPH said in a statement to CityNews.
Wastewater samples can provide a broader view of the impact of COVID-19 because studies have shown both symptomatic and asymptomatic people shed the virus in their stool.
While getting a test is a personal decision, everyone has to use the bathroom at some point and that information becomes available for analysis.
“I think there is a good correlation between what the wastewater surveillance is seeing and what the clinical case information is seeing,” Oswald said. “It is a reliable method and I think it’s only going to get better as we get to do it longer.”
In October last year, Toronto’s Medical Officer of Health did indicate findings from wastewater studies would be used by the agency.
“We are actively participating in those research endeavors and engaging with the researchers on their findings,” Dr. Eileen de Villa said.
There has been no word on how the data has been applied to the work that Toronto Public Health is doing since that time.