Manitoba

Winnipeg wastewater testing reveals mixed picture of COVID transmission in early March

Wastewater testing for the virus that causes COVID-19 reveals a mixed picture of the way the disease may have been circulating in Winnipeg earlier in March.

Viral loads down at North End sewage plant, up at South End and somewhat flat at West End

Wastewater samples are analyzed at the National Microbiology Lab in Winnipeg. (Trevor Lyons/CBC)

Wastewater testing for the virus that causes COVID-19 reveals a mixed picture of the way the disease may have been circulating in Winnipeg earlier in March.

The Public Health Agency of Canada analyzes samples of Winnipeg wasterwater near the city's three sewage treatment plants.

The federal agency determines the relative volume of the virus SARS-CoV-2, which causes COVID-19, and also tests the virus to see which virus variants are dominant.

According to charts published on Monday, the viral load in sewage collected near the North End Water Pollution Control Centre in West Kildonan was dropping during the weeks leading up to March 17.

The North End plant is the largest of the city's three sewage-treatment plants.

The viral load was increasing, however, near the South End Water Pollution Control Centre, located south of the Perimeter Highway in St. Vital.

The viral load was relatively flat near the West End plant, the smallest of the three city sewage-treatment facilities. It's located west of the Perimeter and south of Wilkes Avenue.

Testing revealed the Omicron variant was the dominant virus strain at all three testing locations, with smaller quantities of the Delta variant also present in the samples.

The Public Health Agency of Canada had not updated its Winnipeg charts since it published data for the weeks ending Feb. 22.

Manitoba Public Health received updates in the interim, but declined to release the data on the basis it belongs to the federal government.

Wastewater monitoring is only one indicator of COVID-19 transmission. Public health officials say they also rely on COVID hospitalization and death data, which is now published weekly, and workplace absenteeism reports, which are not made public.

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