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This article was published 08/04/2022 (428 days ago), so information in it may no longer be current.

Remnants of the virus that causes COVID-19 are increasingly being found in Winnipeg sewage, signalling considerable spread of the disease in the community.

On Friday, the National Collaborating Centre for Infectious Diseases posted updated Public Health Agency of Canada wastewater monitoring analysis for the City of Winnipeg.

Sewage is routinely collected from three water-pollution control centres and sent to Winnipeg’s National Microbiology Laboratory to measure remnants of SARS-CoV-2.

Samples collected up to March 31 show viral load in wastewater collected at the South End Water Pollution Control Centre and the West End Water Pollution Control Centre were on the rise, with levels comparable to last May, when the more-severe Alpha variant was circulating widely.

The analysis shows viral load at the two sites has been steadily increasing since late February, when the provincial government began to pull back public-health measures, including vaccination requirements, mask mandates and self-isolation orders.

At the North End Water Pollution Control Centre, the largest facility in the city, levels spiked significantly in the second half of March after dipping to numbers comparable to last July, when the province was in the midst of reopening and reporting a test-positivity rate of about three per cent.

People infected with the virus that causes COVID-19 can shed it in their stool. By monitoring virus levels in wastewater, public health officials can see early indications of increased spread or declines in transmission.

Updated information on the prevalence of COVID-19 variants in Winnipeg wastewater, including Delta, Omicron and its sub-lineages, were not published Friday.

Prior to Friday, the last update from the NCCID was posted on March 28, with analysis showing viral levels were following a clear downward trend at the North End centre, based on samples taken as of March 17. Samples from treatment centres in the south and west ends of Winnipeg had stopped declining at moderate early in March.

The analysis published Friday was consistent with information shared by chief provincial public health officer Dr. Brent Roussin on Thursday, in his first public appearance in about three weeks.

Roussin said wastewater trends indicated increased transmission of COVID-19, driven by the more infectious Omicron B.A2 subvariant. Hospital admissions were also on the rise, though demand on intensive care was declining.

Provincial modelling for severe outcomes related to COVID-19 until about April 21 indicate a “relative” plateau in both hospital and intensive-care admissions.

“We’re not seeing that dramatic decline at this point,” Roussin said Thursday.

He advised all Manitobans to ensure they are up to date on their vaccinations, and said people at significant risk should take extra caution, including wearing a mask in an indoor public place and reducing contacts.

Public health estimates about 60 per cent of Manitobans have been infected with COVID-19, Roussin said.

danielle.dasilva@freepress.mb.ca