COVID-19: Canadian scientists monitoring new variants in airplane wastewater

COVID-19: Canadian scientists monitoring new variants in airplane wastewater

Nicole Ireland, The Canadian Press

Published Thursday, January 5, 2023 4:57 PM EST

TORONTO — As Canadian public health officials question China’s transparency in sharing its COVID-19 surveillance information, scientists are stepping up sewage testing of airplanes to try to provide early warning of potential new variants.

On Friday, Vancouver International Airport will join Toronto’s Pearson International Airport to collect fecal samples from airplane lavatories to determine which coronavirus variants and subvariants could be bringing passengers and crew to Canada.

“A Sentinel system for new variants – that’s where we really see the added value of airport tests,” said Dr. Guillaume Poliquin, vice president of Canada’s Public Health Agency’s National Microbiology Laboratory, told The Canadian Press.

Where does the wastewater analysis take place?

Sampling takes place at Canada’s two busiest airports: Pearson International in Toronto and Vancouver International Airport.

The Public Health Agency of Canada (PHAC) has been working with university scientists since January 2022 to test wastewater from incoming aircraft and terminal buildings in Pearson. The debris from planes coming from both domestic and international destinations were all mixed together, said Lawrence Goodridge, a University of Guelph professor who is one of the researchers.

That will continue, but PHAC is adding a pilot project to separately test sewage from planes arriving from China or Hong Kong.

On Friday, PHAC and the BC Center for Disease Control will begin testing sewage from aircraft “toilet dumps” at Vancouver International Airport, regardless of where it comes from, said Trevor Boudreau, the airport’s director of government relations.

Then, in the coming weeks, the researchers will launch a pilot study similar to Pearson’s to test samples from aircraft from China and Hong Kong separately, Boudreau said.

“The airports really represent a large segment of people — a lot of them are international travelers coming into the country,” Goodridge said.

“The variants that have been a major public health concern to date have all originated outside of Canada. So it’s a great way to understand what’s coming in, and that data can then be used to make public health decisions.”

Why are planes from China and Hong Kong tested separately?

There has been an explosion of COVID-19 illnesses after the Chinese government lifted strict restrictions. In a Dec. 31 press release, PHAC said China had not provided enough “epidemiological and viral genome sequence data” on these cases.

This includes information about which variants are in circulation and whether new variants are potentially emerging.

“What we’re doing here is taking (wastewater testing) a step further and seeing if we can get more precision with direct aircraft sampling,” Poliquin said.

“Then we’re able to compare that… to data from the pooled samples to get a sense of whether it really adds significant value, what kind of additional information does that give us?”

How does the wastewater analysis work?

What comes out of airplane lavatories is “sewage soup” of virus strains and variants from hundreds of thousands of people, Goodridge said.

Trucks transport the wastewater to a central facility where scientists collect samples.

The first part of the process is to separate the solids and liquids in the waste and remove any “impurities” — like fibers and chemicals — that might interfere with the analysis process, Poliquin said.

Then the ‘clean sample’ undergoes a process that analyzes the genetic material present – specifically the RNA of the virus. This process, called “genomic sequencing,” uses computer algorithms to find COVID-19 variants.

Genome sequencing allows scientists to not only find variants and subvariants they are already familiar with, but also to see anything that looks unusual or new.

Then PHAC can look at any unique mutations and compare them to what they’ve observed clinically, such as: B. the variants they found through PCR testing. They can also compare the results with data they get from other countries about what variants are in circulation.

A new Omicron variant that PHAC is currently monitoring is called XBB.1.5. Data from the Centers for Disease Control and Prevention (CDC) from the last week of December suggests the variant accounts for about 40 percent of COVID-19 cases in the US, and the UK is also reporting a spike.

As of Wednesday, the agency was aware of 21 cases of XBB.1.5 in Canada and said it “is currently considered to have only been detected sporadically,” an email said.

Where else are wastewater analyzes used?

Ontario alone has more than 175 sites conducting wastewater testing for COVID-19, said Rob Delatolla, an environmental engineer at the University of Ottawa. Sewage testing helps inform public health about how much COVID and what types are spreading in cities and communities, as well as vulnerable neighborhoods, First Nations and hospitals.

COVID-19 has led to a dramatic increase in sewage testing, Delatolla said, and it’s now being used to detect influenza and RSV as well.

Goodridge of the Pearson Airport Wastewater Testing Project specializes in food microbiology and used wastewater monitoring to detect foodborne diseases before the COVID-19 pandemic.

It has also been used in the past to detect polio, he said.

Sewage testing at airports and airplanes has proven invaluable, Goodridge said.

“I would like to see this expanded to (other) major international airports in Canada,” he said.

“We see what’s coming in, you know, in real time.”

This report from The Canadian Press was first published on January 5, 2023

Canadian Press health reporting is supported by a partnership with the Canadian Medical Association. CP is solely responsible for this content.

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