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University of Calgary researchers check on monitoring equipment as they track traces of COVID-19 in the waste-water system in Calgary on July 14, 2021.Jeff McIntosh/The Canadian Press

Waste-water surveillance indicates the Omicron surge in COVID-19 cases appears to have plateaued or even begun to fall in major cities across British Columbia, Alberta and Ontario, but this type of monitoring is carried out on less than two-thirds of Canada’s population.

Sampling sewage to find population-level transmission trends is one of the most reliable methods of tracking the spread of COVID-19 as the swift spread of Omicron has swamped testing regimes across Canada.

Most waste-water testing programs are concentrated in Ontario and Alberta, where those provinces have invested millions of dollars in networks of researchers. Results from the testing across the country remain private for all but those living in a handful of cities where people can go online and get recent readings to help them with their daily calculus of which activities may be too risky during the current stage of the pandemic.

The epidemiologists, engineers and microbiologists doing this work say they have proved the value of this nascent science and now need governments to step in to continue sifting through the samples that will help officials – and the public – get a head start on confronting subsequent waves of the novel coronavirus or even future pandemics.

SIGNALS IN THE SEWAGE

Many people with COVID-19 shed the virus in their stool, regardless of whether they have symptoms or are able to get confirmation through a test from their public-health authorities. While official counts of active cases may miss thousands of asymptomatic infections and people unable to secure such a test, experts say wastewater surveillance consistently captures most of the population with COVID-19 and offers a window into trends in overall community transmission. Wastewater can also provide an early warning for possible outbreaks at a more granular level, if sewage is sampled from locations such as university dorms or homeless shelters. Citywide data collected by the universities of Ottawa, Alberta and Calgary show that wastewater SARS-CoV-2 values strongly correlate with cases confirmed in the community.

COVID-19 in wastewater signal* (left scale)

Seven-day rolling average in reported new

COVID-19 case (right scale)

OTTAWA

0.0015

1,000

800

0.0010

600

400

0.0005

200

0

0

July

2020

Oct.

Jan.

2021

April

July

Oct.

Jan.

2022

EDMONTON

0.012

2,500

0.010

2,000

0.008

1,500

0.006

1,000

0.004

500

0.002

0

0.000

July

2020

Oct.

Jan.

2021

Apr.

July

Oct.

Jan.

2022

*These values are different in both graphs because the two groups of researchers use different methods to control for the amount of fecal matter produced in the cities.

MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE:

UNIVERSITY OF OTTAWA; UNIVERSITY OF ALBERTA;

UNIVERSITY OF CALGARY

SIGNALS IN THE SEWAGE

Many people with COVID-19 shed the virus in their stool, regardless of whether they have symptoms or are able to get confirmation through a test from their public-health authorities. While official counts of active cases may miss thousands of asymptomatic infections and people unable to secure such a test, experts say wastewater surveillance consistently captures most of the population with COVID-19 and offers a window into trends in overall community transmission. Wastewater can also provide an early warning for possible outbreaks at a more granular level, if sewage is sampled from locations such as university dorms or homeless shelters. Citywide data collected by the universities of Ottawa, Alberta and Calgary show that wastewater SARS-CoV-2 values strongly correlate with cases confirmed in the community.

COVID-19 in wastewater signal* (left scale)

Seven-day rolling average in reported new

COVID-19 case (right scale)

OTTAWA

0.0015

1,000

800

0.0010

600

400

0.0005

200

0

0

July

2020

Oct.

Jan.

2021

April

July

Oct.

Jan.

2022

EDMONTON

0.012

2,500

0.010

2,000

0.008

1,500

0.006

1,000

0.004

500

0.002

0

0.000

July

2020

Oct.

Jan.

2021

Apr.

July

Oct.

Jan.

2022

*These values are different in both graphs because the two groups of researchers use different methods to control for the amount of fecal matter produced in the cities.

MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE:

UNIVERSITY OF OTTAWA; UNIVERSITY OF ALBERTA;

UNIVERSITY OF CALGARY

SIGNALS IN THE SEWAGE

Many people with COVID-19 shed the virus in their stool, regardless of whether they have symptoms or are able to get confirmation through a test from their public-health authorities. While official counts of active cases may miss thousands of asymptomatic infections and people unable to secure such a test, experts say wastewater surveillance consistently captures most of the population with COVID-19 and offers a window into trends in overall community transmission. Wastewater can also provide an early warning for possible outbreaks at a more granular level, if sewage is sampled from locations such as university dorms or homeless shelters. Citywide data collected by the universities of Ottawa, Alberta and Calgary show that wastewater SARS-CoV-2 values strongly correlate with cases confirmed in the community.

COVID-19 in wastewater signal* (left scale)

Seven-day rolling average in reported

new COVID-19 case (right scale)

OTTAWA

1,000

0.0015

800

0.0010

600

400

0.0005

200

0

0

July

2020

Oct.

Jan.

2021

April

July

Oct.

Jan.

2022

EDMONTON

0.012

2,500

0.010

2,000

0.008

1,500

0.006

1,000

0.004

500

0.002

0

0.000

July

2020

Oct.

Jan.

2021

Apr.

July

Oct.

Jan.

2022

*These values are different in both graphs because the two groups of researchers use different methods to control for the amount of fecal matter produced in the cities.

MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: UNIVERSITY OF OTTAWA;

UNIVERSITY OF ALBERTA; UNIVERSITY OF CALGARY

Robert Delatolla and a team at the University of Ottawa began sampling waste water in Canada’s capital in April, 2020, and five months later, started sending reports on COVID-19 prevalence to the local public-health unit five days a week. Dr. Delatolla, an environmental engineer and professor at that university, says the team is now part of an Ontario-wide network of 175 sites that was given $22-million in provincial funding that ends in March.

Recent data show “good but not great news” that levels of the virus detected by this network have peaked and then plateaued at a high level as schools reopened across the province last week, he said. Unfortunately, Dr. Delatolla said, Ontarians can only look up seven of these regional waste-water breakdowns.

On a conference call earlier this month with public-health leaders across the province, he said he urged them to step up with long-term funding for this monitoring.

“We’ve done the science, we know this works really well – it’s been tested over and over. Right now it’s whether the public-health units are going to take it up and show it and use it,” Dr. Dellatolla said. “Is there going to be a federally funded initiative to stabilize this foundation we’ve established across the country? If not, it’s going to erode.”

Student Patrick D'Aoust places a waste-water collection container inside a pump station on the University of Ottawa campus on April 8, 2021.Adrian Wyld/The Canadian Press

This monitoring can’t predict exact case numbers, but experts say it can discern wider trends in transmission and is analogous to offering a polymerase chain reaction (or PCR) test for a whole city.

Some Canadian researchers had to drop this work just as Omicron began raging, while others with funding are often toiling off the sides of their university desks and don’t have the staff to test daily – a frequency that would improve the data divined from the sludge.

In Quebec, a grant funding a pilot project tracking these data in the province’s biggest cities ended in mid-December.

Sarah Dorner, a professor of source-water protection in the engineering faculty of Montreal’s École Polytechnique, said her team’s funding to monitor five regions, including Montreal, Quebec City and Laval, was only supposed to last six months, but she was able to “squeeze out some extra samples” past that original end date to continue testing into mid-December.

At the time, Quebec’s Ministry of Health and Social Services said the project’s preliminary results didn’t give authorities a useful forecasting tool to make public-health decisions across the whole province.

Provincial testing systems have represented an undercount of those people positive with the virus throughout the pandemic as an untold number of asymptomatic people and others don’t seek out this clinical confirmation. But with PCR testing regimes now overwhelmed by Omicron, Quebec authorities have one less data point to track how the virus is spreading throughout the communities where sewage was being tested, Dr. Dorner said.

“Public health is using these alternative indicators; they do modelling as well to see what the projections are – they’re really relying on that – but I can imagine the uncertainties are quite large and it would be nice to have that [waste-water] information,” she said.

The COVID-19 wasteland: searching for clues to the pandemic in the sewers

New online tool lets Metro Vancouver residents track viral load of COVID-19 found in untreated waste water

British obstetrician John Snow traced the spread of the cholera epidemic in London in the mid-1800s to waste water, a revolutionary approach that helped create the science now known as epidemiology. Starting in the 1960s, scientists began tracking polio rates through sewage surveillance.

But public-health experts in Canada and elsewhere have long ceded the oversight of sewage to environmental experts, with provincial governments mostly monitoring waste water for its potential to contaminate communities and nearby ecosystems, according to Dr. Dorner, Dr. Delatolla and other researchers interviewed by The Globe and Mail.

In B.C., a three-person lab shut down over Christmas for a much-needed vacation just as Omicron began spiking in and around Vancouver. As a result, there was a two-week pause on data collection and the postbreak test results weren’t posted online for nearly a month – leaving the public in the dark about COVID-19 levels found at the five treatment plants in that region.

Natalie Prystajecky, head of environmental microbiology at the BC Centre for Disease Control’s public-health lab, said she is keen to expand the work of the small team she oversees so that it covers people across the rest of province. But to do that, she would need to double her team.

“It will be important in the future as we get out of this wave and we continue to watch to see if COVID-19 is going to be resurgent in hot spots,” said Dr. Prystajecky, who also works full time on other COVID-19 sequencing projects and teaches at UBC. “What we want to be able to do is think: ‘What are we going to be able to do with all this infrastructure with COVID-19 and what can we do next?’”

Across the Rockies, Alberta committed $3.4-million for a team from the universities of Calgary and Alberta to monitor the largest cities, but these data are only collected three times a week.

Casey Hubert, a geomicrobiologist who is one of six co-leads of this group, said that means the data, which are usually published online two days after they are collected, are best suited to highlight major trends over longer periods of time.

Dr. Hubert, a biological science professor at the University of Calgary, said people “shouldn’t stare, they should squint” when taking in the trend lines plotted on the group’s graphs. This surveillance has also been used in a more targeted way to monitor outbreaks in smaller populations, such as university dorms and homeless shelters, he said.

Through the trial and error of past pilot projects, Dr. Hubert and his network of researchers have also found certain settings just don’t work – such as anywhere teens congregate for hours.

“We learned the hard way that high school kids probably don’t poop at school – ‘like, duh!’ – but it didn’t work very well in high schools, go figure,” he said.

Creating a regime to test the sewage system of a major city costs pennies for every person, but monitoring a building that has fewer than a 100 people living in it then using this science to monitor for COVID-19 becomes costly, Dr. Hubert said.

Nationally, the Public Health Agency of Canada says it is involved with sewage surveillance in at least 57 different sites across the country, including projects with Statistics Canada in five major cities that cover almost a quarter of the country’s population: Vancouver, Edmonton, Toronto, Montreal and Halifax. It is also working to monitor sewage in several First Nations communities and remote towns, as well as various prisons.

“Waste-water surveillance provides an alert to public-health officials regarding where COVID-19 may be spreading on a community-wide scale,” spokesperson Anna Madison said in an e-mailed statement. “Waste-water testing provides a true picture of community health in the context of SARS-CoV-2 in the current situation when resources for clinical testing are limited.”

The federal agency is working with provincial and territorial governments to create new testing programs in other municipalities, Ms. Madison’s statement said.

Bernadette Conant formed a national coalition of waste-water academics in April 2020 to begin discussing and solidifying this science as well as reach out to public health officials. This monitoring was used in initial waves of the pandemic as an early warning signal to understand how many people may be carrying the virus without knowing it, Ms. Conant said. Omicron has now fundamentally changed its potential as it becomes a tool to fill in the knowledge gaps in overall community transmission trends, she said.

Ms. Conant, CEO of the non-profit Canadian Water Network, said there is no obvious group that could step up to lead a national waste-water surveillance program, given the autonomy all three levels of government have in the country.

“It’s a quintessential example of the benefits and challenges of the Canadian system, there’s federal, provincial and then there’s national strategies,” she said.

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