Rochester’s wastewater could soon alert city residents to new COVID-19 spikes or signs that the spread is waning.
“We can kind of see what’s going on,” Public Works Director Wendy Turri said of tests for the ribonucleic acid, commonly known as RNA, found in the coronavirus.
The copies of RNA in the more than 13 million gallons of wastewater the city processes daily tend to appear before people know they are sick, since the body starts shedding the virus' RNA three to eight days before symptoms appear.
Recent tests at the city’s Wastewater Reclamation Plant pointed to the current increase in cases. While an Oct. 20 sample carried 8.5 coronavirus RNA copies per milliliter, a sample two weeks later revealed 35.6 RNA copies/mL.
“It’s four times greater, so we knew things were going to start blowing up,” Turri said.
However, the results have been delayed because the city outsources the testing, which can take seven days, meaning the Nov. 4 increase wasn’t discovered until confirmed positive cases started increasing throughout the county.
To overcome the delay, as well as increase monitoring, the city is partnering with Olmsted County Public Health, Mayo Clinic and University of Minnesota Rochester.
Caroline Sussman, a Mayo Clinic researcher, is helping coordinate UMR students to test samples provided by the city. They are using Mayo Clinic lab space.
“We should have the results in a couple days,” said the associate director of the Office of Postdoctoral Affairs and Research Training.
Sagar Chowdhury, Olmsted County’s environmental health manager, said cutting the turnaround time for test results will provide a four-day jump-start to respond to increased spread.
“With COVID, there is a lot of catch-up that you are playing,” he said.
In addition to looking at citywide numbers, the project also seeks to focus on specific parts of the city or individual locations to monitor for outbreaks.
Participants said efforts could focus on long-term care facilities by monitoring wastewater.
Chowdhury said seeing an increase of the RNA in a facility’s wastewater could spur COVID-19 tests for all residents and staff, so positive cases could be isolated, preventing larger spread before symptoms appear.
In other cases, he said the project could identify hot spots in the city, leading to increased messages encouraging safe practices or even a mobile testing operation if warranted.
Additionally, Sussman said the results will likely verify what is being seen in testing sites, where questions are sometimes raised about the number of people being tested and whether it’s a true community sample.
She said the wastewater tests provide an unbiased view of what is happening in a single area or throughout the city.
“You can’t argue,” she said of the samples. “Everybody is putting their waste in the water. You can’t avoid it; you can’t escape it. Everybody puts in generally the same amount every day.”
To ensure the accuracy of the testing, Mayo Clinic is setting up required protocols and will start by testing samples that compare to what the city is outsourcing to ensure the results match.
“We’re in the validation stage now,” Sussman said.
Meanwhile, the city and county are working to identify sites to start collecting 24-hour samples.
“We’re still figuring everything out,” said Corey Bjornberg, the city’s process control engineer working on the project.
It could take weeks to start regular testing, but Sussman said the project will provide benefits throughout the pandemic, even as vaccines appear, since the virus will likely linger in the community.
“I think this disease is going to be living with us for a while,” she said, adding that Mayo Clinic researchers are also hoping to use the samples to track potential mutations in the coronavirus, as well as identify where local strains originated.
“The idea with the team is to get the most and best information out of the effort that we can,” she said.
Some of that information will likely provide insights into the success of future vaccines as they emerge.
“We could see the drop in the concentration of the sample, essentially showing the effectiveness of the vaccine,” Chowdhury said.
Whether it’s catching increased spread before it happens or tracking lowering numbers, Chowdhury said he anticipates a variety of benefits to the work being planned.
“If we can save a life or two, or we can provide relief in any capacity, we’re going to consider it a success,” he said.