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 information from its COVID-19 surveillance, scientists are stepping up testing of sewage from airplanes to try to get an early warning of potential new variants.
On Friday, Vancouver International Airport will join Toronto’s Pearson International Airport in sampling fecal material from airplane toilets to determine what variants and subvariants of the coronavirus passengers and crew may be carrying into Canada.
“A surveillance system for new variants — that’s really where we see the added value of airport testing,” Dr. Guillaume Poliquin, vice-president of the Public Health Agency at the National Microbiology Laboratory of Canada, told The Canadian Press.
Where will the wastewater be tested?
Sampling will take place at the two busiest airports in Canada: Pearson International in Toronto and Vancouver International Airport.
The Public Health Agency of Canada (PHAC) has actually been working with university scientists to test waste water from arriving aircraft as well as terminal buildings at Pearson since January 2022. Waste from aircraft coming from both domestic and international destinations , are 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 wastewater from planes arriving from China or Hong Kong.
On Friday, PHAC and the BC Center for Disease Control will begin testing “toilet” wastewater from planes 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, researchers will begin a pilot study similar to Pearson’s to separately test samples from planes coming from China and Hong Kong, Boudreau said.
“Airports do represent a large portion of people — many of whom are international travelers coming into the country,” Goodridge said.
“Variants that have so far been major public health concerns have originated outside of Canada. So it’s a great way to understand what’s coming, 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 the COVID-19 disease since the Chinese government lifted strict restrictions. In a news release issued on December 31, PHAC said China had not provided enough “epidemiological and viral genome sequence data” for these cases.
This includes information about what variants are distributed and any new ones that appear.
“What we’re doing here is taking (wastewater testing) one step further and seeing if we can get more precision by doing direct sampling from an airplane,” Poliquin said.
“Then we’ll be able to compare that … with the pooled sample data to get an idea of whether it really adds significant value, what type of additional information does that give us?”
How does wastewater testing work?
What comes out of airplane toilets is a “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 take samples.
The first part of the process is to separate the solids and liquids in the waste and remove any “contaminants” — such as fibers and chemicals — that can interfere with the analysis process, Poliquin said.
The “pure sample” is then put through a process of analyzing the genetic material – specifically the RNA from the virus – that is present. This process, called “genomic sequencing,” uses computer algorithms to find variants of COVID-19.
Genome sequencing allows scientists not only to find variants and subvariants they are already familiar with, but also to see anything that seems unusual or new.
PHAC can then look at any unique mutations and compare them to what they’ve seen clinically, such as the variants they’ve found through PCR testing. They can also compare the findings with data they get from other countries about what variants are spreading.
A new variant of Omicron that PHAC is currently monitoring is called XBB.1.5. Centers for Disease Control and Prevention (CDC) data from the last week of December suggest the variant accounts for about 40 percent of COVID-19 cases in the U.S., with the U.K. also reporting an increase.
As of Wednesday, the agency was aware of 21 cases of XBB.1.5 in Canada and said it is “currently considered to be only sporadically detected,” it said in an email.
Where else is wastewater testing used?
In Ontario alone, there are more than 175 sites testing wastewater for COVID-19, said Rob Delatola, an environmental engineer at the University of Ottawa. Wastewater testing helps public health inform how much and what types of COVID are spreading in cities, as well as vulnerable neighborhoods, First Nations and hospitals.
COVID-19 has caused a dramatic increase in wastewater testing, Delatola 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 illnesses before the COVID-19 pandemic.
Historically, it was also used to detect polio, he said.
Testing wastewater at airports and on airplanes has proven invaluable, Goodridge said.
“I would like to see this expand to (other) major international airports in Canada,” he said.
“We see what’s coming into the country, you know, in real time.”
This report by The Canadian Press was first published on January 5, 2023
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Canadian Press health coverage is supported through a partnership with the Canadian Medical Association. CP bears all responsibility for this content.
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