As wastewater testing at Toronto Pearson airport expands, it becomes more challenging: researcher

The wastewater monitoring project conducted by the universities of Guelph and Waterloo at Toronto Pearson International Airport is entering its second year, but has gotten more complicated as the COVID-19 virus has mutated, according to one of those involved.

Dr. Lawrence Goodridge, a professor at the Ontario Agricultural College, has led U of G’s efforts in helping to study the wastewater from planes and terminals at the airport in Mississauga.

He says there are now more than two dozen subvariants of the virus being located in the wastewater.

“In recent months, it’s become increasingly difficult to detect new variants in wastewater, because at any given time, we are finding evidence of 20 or 25 subvariants,” he stated in a release from the school.

The researchers don’t actually test for subvariants but are looking for mutations of subvariants such as the “Kraken” XBB.1.5 through genomic sequencing.

In addition, a  few weeks ago, the Public Health Agency of Canada announced that the project was expanding to conduct separate testing of the wastewater from flights arriving from China and Hong Kong.

What makes it tough is attempting to find the specific new variants of concern as they wade through all of the different subvariants.

“If you think about it as a puzzle, it used to be just a 10-piece puzzle. Now, it’s 1,000 pieces and most of those pieces look the same, because they are all Omicron.” he said.

“On top of that, it’s been mixed up with 10 other jigsaw puzzles and those pieces also look the same. So, we’re looking for these unique pieces and we are running into pieces from other puzzles that aren’t important.”

Goodridge told Global News that the research is being conducted in an effort to show the value of wastewater testing

“Currently we are just looking for SARS-CoV-2,” he said in an email. “One goal of this pilot is to demonstrate the utility of wastewater surveillance, which could be applied to other diseases in the future.”

The school says that wastewater testing has helped track the spread of the virus across Ontario as the clinical testing of people has declined.

The University of Guelph says that using the wastewater results at the airport and in other places is only a piece of the puzzle in identifying the spread of COVID-19 in Ontario as it goes hand-in-hand with other indicators to track transmissions trends.

Goodridge says that the testing at one of the busiest international airports on the continent has allowed Canada to have a better a better public health response to COVID-19.

“Ideally, sampling should be accomplished as non-invasively as possible, and at sites where large numbers of people from different international locales, enter the country,” he said.

“This approach increases the chances of detecting a VOC soon after it enters the country. Wastewater testing at Person checks all of these boxes. It is non-invasive, with a single wastewater sample providing information from all flights, and in a cost effective way; and Pearson regularly sees large numbers of international travellers.

“Ideally such a program would be expanded to other major international airports in Canada, including Vancouver (which recently began wastewater testing), Calgary, and Montreal.”

© 2023 Global News, a division of Corus Entertainment Inc.

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