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Quebec’s Health Department has begun releasing data on the presence of COVID-19 in wastewater.

The government says the data can provide early warning of new pandemic waves or the emergence of new variants.

Quebec has been screening wastewater for COVID-19 in Quebec City and the Montreal area since late March but only began releasing the data today.

The seven-day average of wastewater collections suggests a decline in the concentration of COVID-19 in wastewater in Quebec City, while in Montreal, the data suggests a stable concentration.

Dominic Frigon, a McGill University civil engineering professor who helped develop Quebec’s wastewater screening program, says the data can be useful for detecting trends but adds that COVID-19 levels in wastewater don’t directly correlate to case counts.

Frigon says wastewater data can also be affected by other factors, such as rain, which dilutes the sewage for testing.

The federal government has been publishing wastewater screening data – including for the Montreal area – online since early May 2022.

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