Calgary wastewater samples show recent spike in coronavirus
A project that monitors Calgary sewage for the presence of the virus responsible for COVID-19 is showing a significant spike since mid-march.
The data, which is available in graph form on a public website, shows levels of the virus trending upward and sample points higher than previous highs seen in mid-december, when Calgary was in its second wave.
Dr. Michael Parkins, associate professor in the department of medicine at the University of Calgary and section chief of infectious disease for Alberta Health Services' Calgary zone, is one of the researchers involved with the project. He said previous wastewater sample numbers have predicted future COVID-19 case numbers.
The research data available online comes from wastewater collected from three City of Calgary wastewater plants.
The researchers have been able to combine data from the three plants into a single number that represents the whole city, and roughly predict future COVID case counts with an algorithm.
“What we're finding in wastewater with the peaks is (they suggest) what's going to happen six days from now,” he said.
“Tracing things over time — using this algorithm — our ability to predict things over a 95 per cent confidence interval is very strong, six days later.”
He said since March, some areas of the city have shown more increase than others, but all locations are finding more of the virus than in February.
“We're forecasting with a grain of salt but certainly the persistent, consistent increase of SARSCOV-2 is concerning, and the fact that what we're seeing now is surpassing what we saw in Wave 2 is particularly concerning,” said Parkins.
He said working with wastewater presents problems, because he and his colleagues don't get homogeneous samples.
Instead, they've developed techniques to compress an entire day's worth of wastewater into a single sample, or look for markers in the sample that help them measure the relative amount of fecal matter.
“What's not necessarily important is one data point, but trending points,” he said.
Alberta's COVID-19 case numbers have been on a steady upward trend since early March, climbing from the mid-300s per day to more than 1,000 cases per day,
On Monday, Premier Jason Kenney said the province could see that number double again.
“Right now, we're on track to hit probably 2,000 average daily cases in the near future and quite possibly 20,000 active cases,” the premier said.
In a statement, AHS said the health authority is pleased to partner with the university and city on the project.
“Anything that helps provide earlier detection — at the community level — of COVID-19 outbreaks and how they are spreading, would be a valuable tool in our response to the pandemic,” reads the statement.
“As project partner, receiving results in real time, AHS integrates this research project's data with other clinical data to better understand COVID -19 dynamics in the community.”
Parkins and the other researchers have been collecting wastewater data from more specific locations as well, including six Calgary communities and certain large buildings such as schools and dormitories.
That more specific data isn't being made public, due to privacy concerns.
“The more granular we get, the more issues of confidentiality creep in. But we are seeing more SARS-COV-2 activity in the northeast than we've seen in the southwest, for example,” he said.
That finding matches up with data from throughout the pandemic, consistently showing Calgary's northeast quadrant bearing the brunt of the virus.
Parkins said this type of sampling and testing has great value because it doesn't discriminate.
“It has a very significant potential to capture everything, and it's great in that it's well-balanced and it's inclusive,” he said. “It includes all aspects of society. So we're not looking at one group more than another, we're looking at everybody equally.”