Sewage monitoring: wastewater can fill the gap in COVID-19 testing-experts say-nationwide

Some jurisdictions limit PCR testing COVID-19 (new coronavirus infection) Others, who are increasingly overwhelmed by the demands of diagnosis, emphasize that the daily number of cases no longer gives a complete picture of the virus level within the community.

However, what we flush to the toilet may help us better understand the prevalence of COVID-19.

Researchers from all over the country have been working on it Wastewater Monitor from the beginning of the pandemic and look for traces of virus in the sewage to see how the virus spreads.

People involved in the painstaking process say it is not a complete measurement of COVID-19 levels, but it does help show where viral activity is transmitted.

And when test capacity is exceeded and cases are underreported, wastewater surveillance is especially beneficial, they say.

“We are currently experiencing this problem and have reached the limits of our testing,” said Mark Servos, a researcher at the University of Waterloo, who is involved in surveillance at many sites in Ontario. “But wastewater doesn’t care if clinical trials are being conducted or if people are symptomatic or asymptomatic.

“Anyone who poops on a pipe will be included in the analysis.”

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Huge COVID-19 wastewater spike in Saskatchewan.No cause for alarm: Researcher

Ontario announced Thursday that it will tighten the eligibility of PCR tests and book publicly funded diagnoses for high-risk individuals who are most vulnerable to symptomatic and severe illness.

Manitoba said this week that it is limiting the availability of PCR at test centers, instead distributing takeaway tests on those sites and telling people to return only if self-management results are positive. I asked.

Measures aimed at saving finite amounts of PCR will lead to underreported cases when the more contagious variants of Omicron are rapidly prevalent.

Dr. Christopher Modi, an infectious disease expert at the University of Calgary, said PCR may have revealed only “1 in 6 or 1 in 8” actual cases. However, that number can be exacerbated by those who rely on the results of rapid tests that are not officially recorded, or those who have not been tested at all.

“We need to know what that number is,” he said, adding that wastewater may help fill some gaps.

“I would like to say that wastewater is a very valuable tool for assessing the burden of illness.”

By monitoring weekly trends in wastewater, it is possible to show not only the amount of virus circulating, but also which variants are promoting the infection.

Data from Saskatoon showed that last week, urban wastewater increased viral load by 87.7%. This includes an 808.2% increase in the traces of Omicron detected.

Meanwhile, surveillance updated Friday from the Waterloo region of Ontario showed that the COVID-19 signal surged in Kitchener, Cambridge, and Waterloo last week.

The process of wastewater monitoring involves collecting samples in a water treatment plant and cleaning them to separate and measure trace amounts of COVID-19 particles.

Servos called it a “tricky” and “boring” effort, but results can improve within a few hours.

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COVID-19 by community: New localized data show virus levels in Calgary wastewater

Forecast of occurrence

Samples are collected daily in some jurisdictions, including Ottawa, which launched the program in April 2020. In other jurisdictions, sewer samples are taken and analyzed several times a week.

Robert Delatra, a civil engineer at the University of Ottawa, who monitors water samples, said:

Deratra said a similar pattern was seen last fall, when Thanksgiving was followed by pressure on test capabilities.

“The number of tests has decreased, so the daily numbers haven’t skyrocketed … but wastewater has continued to grow,” he said.

“The number of (PCR) tests we do is (top-out), but wastewater is unaffected. In that sense, its value is just being seen.”

However, Quebec has recently shrunk as some states have stepped up wastewater monitoring.

Sarah Dorner, a professor at Polytechnique Montreal, said the six-month pilot project funded by Fonds de recherche du Quebec and the Molson and Trottier Foundation ended in early December.

“We didn’t have the money to continue,” she wrote in an email, adding that her team observed “a rapid rise in SARS-CoV-2” in Montreal’s wastewater before the project was abandoned. I did.

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Coronavirus outbreak: WHO analyzes wastewater to determine COVID-19 circulation worldwide

In the era of COVID-19, which was previously used worldwide to monitor polio, wastewater monitoring practices are not new.

However, while Delatolla and Servos state that wastewater monitoring is a useful and additional tool, this process has its drawbacks. Monitoring can only show what is happening in a particular locale being monitored, not the entire state.

Although wastewater data cannot indicate the severity of the case, Delatolla noted that some areas of sewage had lower levels of COVID-19 compared to last spring’s delta waves. This may reflect the low viral load currently shed by the highly vaccinated public.

According to Servos, fluctuations in wastewater due to environmental factors such as snowmelt flowing through sewers can further dilute the sample, but analysis can also be hampered by the capabilities of the lab.

“We are not a commercial lab. We are a university lab,” he said. “We can do (test) pretty quickly, but it takes a lot of effort … and it’s hard to catch up on a daily basis.”

According to Modi, one of the benefits of monitoring COVID-19 in wastewater is that it helps health authorities to quickly show an increase in cases and predict imminent outbreaks.

“If a surge begins to be seen in a particular community, we can expect the case to continue fairly quickly,” he said.

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