Wastewater surveillance data for COVID ‘remarkable’ — but Hamilton has rejected it

Hamilton public health is not using or disclosing wastewater surveillance that is increasingly being relied on provincially to measure COVID-19 trends.

It's not something that has worked in Hamilton to date," medical officer of health Dr. Elizabeth Richardson said in a statement.

However, leaders in the provincewide program refute Hamilton's rejection of the real-time indicator used to track transmission, especially since PCR testing stopped being available to the general public on Dec. 31.

The data is remarkable," said Robert Delatolla, whose University of Ottawa team detects COVID in Hamilton's wastewater. I don't think they're using the resources that are available to them to understand the data."

Delatolla has been analyzing wastewater surveillance from the Woodward Avenue and Dundas treatment plants since July 2020 and says the city has one of the largest data sets in the country.

A large amount of resources have been invested in Hamilton," said Delatolla, who is a civil engineering professor. Hamilton has not made their data public - they have not been willing to do that."

Public health said in a statement that wastewater surveillance does not support a greater understanding of the COVD-19 pandemic locally."

But Delatolla disputes that claim, saying wastewater has been a strong early indicator of COVID hospitalizations in Hamilton since 2020.

The scientific director of Ontario's COVID-19 Science Advisory Table agrees that wastewater surveillance is reliable.

I'm not aware of any evidence to suggest that the wastewater data in Hamilton would behave differently than what we see in the surrounding public health units," said Dr. Peter Juni.

The leader of the surveillance team at the University of Waterloo also found Hamilton's position puzzling.

My impression is that they are generating really good results, they're showing really good trends," said Mark Servos, the Canada Research Chair in Water Quality Protection.

Richardson said Hamilton's data is too variable." But Servos said all wastewater surveillance data is highly variable."

Imagine you are taking a sample out of millions of litres of things that people are putting in the sewer so it's very difficult," said Servos. But all of the sites that I've worked at, we get very nice trends - really good data. It parallels the clinical cases extremely well."

Ontario's chief medical officer of health Dr. Kieran Moore called wastewater a key indicator to track transmission levels in communities."

We are paying close attention to our wastewater surveillance," Moore said at a provincial briefing Thursday.

Delatolla says $22 million has been invested by the province to expand the Wastewater Surveillance Initiative to 175 locations covering all Ontario public health units.

The science table has added wastewater to its COVID dashboard and a number of public health departments report on it, including Ottawa and Waterloo.

They've become very reliant on it," said Servos. When the clinical testing stopped then wastewater became the only real independent tool we had to assess the community prevalence."

Juni does not expect widespread PCR testing to return any time soon so wastewater will be key going forward.

It will be one of the measures we need to use because we will not be able to have a sustainable clinical testing system that is also affordable," said Juni. The idea would be to optimize the wastewater surveillance."

Wastewater is economical and more inclusive because it doesn't rely on the public's ability to access it.

If you poop, you're going to get included," said Servos. Everybody poops so wastewater is a pretty good metric."

Richardson said public health has found test positivity and hospitalizations to be far more representative of COVID-19's current prevalence."

But Delatolla points out there are issues with relying too heavily on hospital admissions.

Hospitalizations is a lagging indicator," said Delatolla. It's a great indicator, but it's almost too late. You want to protect your hospitals, protect your health resources. Wastewater allows you to do that."

He gives examples of wastewater providing early warning of COVID on university campuses and at long-term care homes.

We were tracking Omicron in the wastewater as it came into our cities," said Delatolla. Wastewater was showing us in real time what was happening with the onset of Omicron in multiple cities across the province."

Public health claims it continues to meet with the researchers to try to better understand and reduce the variability in the data."

Delatolla said: We're always available to talk with them."

We have meetings every two weeks and I hope they come. I hope they engage further with us," he said. I really hope that Hamilton uses the data."

Joanna Frketich is a health reporter at The Spectator. jfrketich@thespec.com