Hamilton’s wastewater surveillance for COVID made public
Wastewater surveillance to detect COVID-19 has been made public in Hamilton for the first time.
The Spectator was provided the data this week after public health gave the go ahead to the University of Ottawa team that has been analyzing COVID in Hamilton's wastewater since July 2020.
Starting Friday, wastewater surveillance will be added to the city's COVID dashboard.
The disclosure is one step toward a resolution to the dispute between the researchers and public health over whether wastewater surveillance shows local COVID trends.
Public health has long claimed - including in a statement Thursday - that it's not something that has worked as a predictive measure in Hamilton to date."
In contrast, lead researcher Robert Delatolla has called the data remarkable" and said it has been an early predictor of hospitalizations for over 18 months now.
The data provided to The Spectator appears to show wastewater has been providing early warning of cases, hospitalizations, intensive care unit (ICU) admissions and deaths.
Delatolla said there has been some effort to come to an understanding since The Spectator started publishing stories on the divide March 5.
I've been getting a lot emails and I'm having phone discussions with public health," said Delatolla, a civil engineering professor. I think there's movement here in terms of public health coming to the table ... I'm really excited to see a conversation started again."
It's significant because the province has been increasingly relying on wastewater since PCR testing hasn't been available to the general public since Dec. 31.
Health Minister Christine Elliott has called the data the canary in the coal mine that can tell us if there is something that we need to be concerned about that's coming in the future."
The province's chief medical officer of health has said it is a key indicator" that is being monitored closely.
The Ontario COVID-19 Science Advisory Table has added wastewater to its dashboard and a number of public health departments report on it.
Data from the Woodward Avenue and Dundas treatment plants show wastewater detected COVID cases roughly 10 days before testing from July 2020 to December 2021. Hospitalizations and intensive care unit (ICU) admissions were predicted about 14 days in advance, while deaths were around 20 days ahead.
The wastewater data has been a very good indicator," said Delatolla. Really, overall, what you do see is the wastewater is an indicator of disease burden."
He particularly notes the accuracy of wastewater surveillance when compared to the actual number of cases and hospitalizations.
You can see how close those data sets are," he said. It's remarkable how much they follow each other."
A further mathematical evaluation of the data sets show that there is a strong relation between them, meaning they are very similar," said Delatolla.
Wastewater was less predictive for the Omicron wave that started Dec. 1, but still roughly accurate. Hospitalizations were detected about three days early, ICU admissions dropped to roughly two days in advance, while deaths were nine days.
For the omicron wave, it's not as early an indicator as it has been and we're seeing that across other sites too," said Delatolla.
The data clearly shows the wastewater surveillance and cases diverging as widespread PCR testing came to an end, which is why resolving the dispute between public health and the researchers is critical.
Definitely, we've lost the key metric of testing an abundance of people across the province," said Delatolla. Now that we don't have that, I think wastewater can easily be used as a metric to replace that."
Joanna Frketich is a health reporter at The Spectator. jfrketich@thespec.com