Makanont: COVID-19 levels being monitored in Waterloo Region's sewage

WATERLOO REGION — “Everyone poops” and those infected with COVID-19 flush fragments of the virus into Waterloo Region’s sewage system, where the levels are being closely monitored.

Wastewater samples are being taken multiple times a week at the Cambridge, Kitchener and Waterloo treatment sites for a surveillance project that’s a partnership between the region and the University of Waterloo.

“The advantage of monitoring the virus in wastewater is it allows us to monitor COVID-19 infection in the whole community, regardless of whether symptoms are present or test results are available,” Arianne Folkema, an epidemiologist at the public health department, told the board of health at this week’s meeting.

Now the public can see data from that monitoring on a new dashboard that will be updated weekly on Wednesdays. Charts compare confirmed COVID-19 cases over time with wastewater signal data.

“Confirmed case data and the wastewater data are in alignment. When the case numbers increase or decrease, we see similar trends with the wastewater virus load,” Folkema said.

Wastewater surveillance for COVID-19 involves testing for fragments of the virus that are shed by both asymptomatic and symptomatic people. It would also capture those who choose not to get tested or face barriers to getting tested.

The data can be used as a surveillance tool alongside other public-health indicators to identify trends in community transmission to inform decisions and target resources.

“In more scientific terms: everyone poops and I hope everyone enjoys that statement. The truth is by sampling and analyzing wastewater signal we are able to monitor transmission of COVID-19 for everyone that contributes to the sewer system including those that never experience symptoms,” Folkema said.

Testing began in early January at the three largest sewage treatment plants that serve about 85 per cent of region’s population. When confirmed COVID cases were mapped to those sewer-shed areas, they covered about 82 per cent of all cases in the region from January to April.

“Basically demonstrating that the work that we’re doing represents a large majority of the Waterloo Region population,” Folkema said.

Along with monitoring the whole community for the virus, the wastewater testing can also keep tabs on variants of concern. Currently they’re tracking the B.1.1.7 variant, but work is being done to test for others.

There are some limitations, including environmental factors that affect wastewater data such as heavy rainfall that dilutes samples. Based on current sampling methods, the data can only be interpreted at the level of the catchment area and not to detect trends in specific neighbourhoods.

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“There are lags due to the time that it takes to process the samples, which limits our ability to identify real-time changes in trends. However, we have found that trends have paralleled clinical cases well.”

Find the dashboard at www.regionofwaterloo.ca/en/health-and-wellness/covid-19-wastewater-surveillance.aspx.