Wastewater could help offset overwhelmed COVID-19 test sites

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As Quebec and other provinces update their testing guidelines in response to the record increase in new COVID-19 cases, many experts are warning that the daily COVID-19 reports released by these governments no longer provide an precise description of the progress of the pandemic.

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But the content of a community’s wastewater could provide a more accurate picture.

As scientists across the country have tracked the presence of COVID-19 in wastewater since the start of the pandemic, they say this process is particularly valuable as public health authorities struggle to track the spread of the highly variant. transmissible Omicron.

“We have this problem where we have reached the limit of our ability to administer screening tests,” said Mark Servos, researcher at the University of Waterloo. “But sewage doesn’t care if people have been tested or if they are asymptomatic.

“Everyone who goes to the bathroom is included in our analysis. “

The process is tedious and laborious, according to Servos, but results can be achieved in a matter of hours. And while the analysis of wastewater does not provide exact data on the number of COVID-19 cases, it may allow public health officials to identify areas with high contagion rates.

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According to Christopher Mody, an infectious disease specialist at the University of Calgary, positive results from PCR tests represent only about one-sixth or one-eighth of the total number of cases. This gap is expected to widen as more people rely on self-administered rapid tests or simply do not get tested.

“We need to know what the real number is,” Mody said, adding that analysis of the wastewater could help make up for the lack of data. “I would say that wastewater is an extremely useful tool in assessing the magnitude of the disease burden. “

In addition to measuring the extent of transmission, the researchers say that regular wastewater testing for COVID-19 would allow public health officials to identify dominant variants in the community.

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Data collected last week in Saskatoon, for example, showed an 87.7% increase in viral load in the city’s wastewater, including a peak of 808.2% in the presence of the Omicron variant.

Despite the potential benefits of wastewater testing in Quebec, where various factors have led to the underreporting of new COVID-19 cases, the province recently stopped funding a project doing just that.

Sarah Dorner, a professor at Polytechnique Montreal who had helped lead the research on COVID-19 wastewater samples, said funding for the six-month pilot project ended in early December.

“We had no more funding to continue,” she wrote in an email, adding that her team had observed “a rapid increase in SARS-CoV-2” in Montreal wastewater just before the shutdown. of the project.

“Public health is no longer interested,” Dorner told the Montreal Gazette at the time.