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By Chris Brown

Data independent of clinical testing

COVID in wastewater a trend to watch, say researchers

Jan 14, 2022 | 4:32 PM

MEDICINE HAT, AB – Wastewater monitoring has emerged as an important tool for health officials as cases of the Omicron variant have overwhelmed the province and limited testing capacity in the fifth wave.

Many communities are experiencing levels of COVID infection never before seen during the pandemic.

Medicine Hat is so far bucking that trend, in part because of a local spike in August and September.

The last posted results for Medicine Hat, from Jan. 10 show 55.6 genomic copies (gc) per one millilitre (mL) of wastewater. That’s far from our Sept. 8 spike of 412 genomic copies per one millilitre of wastewater.

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“The documents show some infection and the prevalency that Medicine Hat, it’s not that really higher right now but that does not mean it’s not going to go up,” explains project lead Dr. Xiaoli Pang. “Maybe next week suddenly it comes up. Because usually we see the big cities first being hit, then it goes to small towns, small cities.”

Pang is molecular virologist program leader at Alberta Precision Laboratories and University of Alberta professor in the Department of Laboratory Medicine & Pathology.

Elsewhere in southern Alberta, traces of COVID in Lethbridge wastewater spiked at 210 gc per one mL of wastewater on Jan. 4. The previous high was 101 in March 2021.

Traces of SARS-CoV-2 RNA, the virus that causes COVID, can be found in the fecal matter of pre-symptomatic, asymptomatic and symptomatic people.

She says wastewater testing is non-discriminatory because everybody who is infected sheds the virus in their stools and it is distributed in the sewage system.

“We are not able to identify who is infected but more what’s in the community prevalence and the disease burden,” she says.

Dr. Bonita Lee is a pediatric infectious disease physician at Stollery Children’s Hospital and associate professor in department of pediatrics at University of Alberta.

She says while researchers are quite confident that there is good correlation between wastewater SARS-CoV-2 RNA and disease burden, it is important to keep in mind it is early in the life of the Omicron variant in Alberta.

“We are still learning whether fecal shedding of Omicron and contribution of RNA in wastewater is similar between Omicron and other strains, e.g., Delta; thus we need to be cautious in comparing the absolute level of SARS-CoV-2 RNA in wastewater of various waves in terms of disease burden when the different waves are predominated by different strains,” she explains in a statement.

Researchers at the University of Calgary and University of Alberta have been monitoring the prevalence of COVID-19 in wastewater for a year and a half.

Medicine Hat has been participating since the start and Brooks and Taber joined in December.

At present, 25 cities, town and communities are being monitored now covering about 3.2 million Albertans, and more municipalities are expected to join.