Wastewater monitoring suggests COVID-19 transmission may have peaked in Winnipeg on New Year's Day

Despite record numbers of COVID-19 patients in hospital and multiple daily deaths, there is some evidence the pandemic's current wave could be receding in Manitoba.

Wastewater monitoring conducted by the National Microbiology Laboratory suggests the virus that causes COVID-19 was found in the largest quantities in Winnipeg at the beginning of January.

Samples collected at three out of four locations in Winnipeg — one in each quadrant of the city — suggest the viral load in Manitoba's capital peaked on New Year's Day, Manitoba Public Health said in a statement.

The province is now working with scientists at the National Microbiology Lab to analyze the data, said public health.

The province has yet to conclude the pandemic's current wave of cases is drawing down.

"Wastewater surveillance is one tool and can be a helpful indicator, but there can be considerable fluctuation in the data, which means it needs to be considered in concert with other data," Manitoba Public Health's statement said.

"While this information shouldn't be used in isolation, previous studies have shown that wastewater data can be an early indicator to identify new strains, and increasing or decreasing volumes."

The National Microbiology Laboratory, located on Arlington Street, has been analyzing samples of Winnipeg wastewater since the start of the pandemic.

People who are infected SARS-CoV-2, the coronavirus that causes COVID-19, shed viral RNA in their feces. This shedding can start before infected people even develop symptoms, and can continue for several weeks.

The RNA can be monitored in wastewater and used to detect COVID-19 outbreaks, determine whether infections are rising or dropping and even discern trends, such as the effects of new restrictions or pandemic policy decisions like sending kids back to school.

WATCH | A March 2021 report on how wastewater monitoring helps detect COVID-19: 

"Wastewater surveillance signals do follow trends in cases quite closely," said Anna Maddison, a spokesperson for the Public Health Agency of Canada.

"Therefore, wastewater data allows us to identify large outbreaks, such as the recent Omicron wave, and declines in community transmission due, for example, to public health measures."

Dr. Philippe Lagacé-Wiens, a medical microbiologist at St. Boniface Hospital, said wastewater monitoring became a more important tool after the highly contagious Omicron coronavirus variant became dominant, and transmission became so widespread that most provinces lost the ability to monitor it.