Omicron revelation surfaces in Canadian wastewater

Scientists in Nova Scotia, Canada have said they started detecting the Omicron variant of Covid-19 in local wastewater before it was officially discovered in South Africa in late November.

Last week, Professor Graham Gagnon, director of the Dalhousie University Centre for Water Resource Studies in Nova Scotia, told CBC that they found Omicron in wastewater samples from early November. 

“It was surprising to us to see a viral signal in early November. Only in retrospect were we able to see that it was a variant and not the original,” he said. The cases were confirmed to be Omicron on December 13 and were linked to a Covid-19 outbreak at St. Francis Xavier University in Antigonish.

The Omicron variant was formally identified in South Africa in late November. 

The research director said he was surprised to find the virus in November because students at the residences were all vaccinated and those tested provided negative results. He said the results were passed on to officials at the university who warned students. 

“For us, it's been a successful project,” Gagnon told CBC, adding, “It's a tool that can be used to help make decisions.”

The Dalhousie researchers have been testing wastewater for signs of the deadly virus since December 2020 at four main wastewater treatment plants in Halifax and five student residences on the Dalhousie campus. 

Covid-19 can live longer in the gastrointestinal tract than in the respiratory tract, despite being a respiratory virus. Thus, wastewater testing can be a useful tool for monitoring its prevalence.