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Idaho plans to expand wastewater testing for COVID-19

Boise's Lander Wastewater Treatment facility as seen from the air.
City of Boise
Boise's Lander Wastewater Treatment Facility

Idaho Health and Welfare Bureau Chief and Laboratory Director Dr. Christopher Ball says the state is about six weeks away from standing up new wastewater testing programs for COVID-19 at Idaho's four state universities.

The new capacity will allow more communities to test for the presence of COVID-19.

The city of Boise is one of several in Idaho which has tested wastewater since the beginning of the pandemic. Determining the viral load in a wastewater sample uses the same type of PCR test given to individuals.

"The consistency of this data set in wastewater is a collection of our entire community," said Haley Falconer, Environmental Division Manager with the City of Boise. "We likely can't get that type of data in another way, in a cost effective manner."

After weeks of declines, city officials say they’ve seen a recent uptick of about 10%-15% more COVID-19 in wastewater samples.

For much of the pandemic, "we were seeing, statistically, about a five-to-seven day leading indicator from an increase in viral load in the wastewater to an increase in clinical cases," Falconer said. Simply put, an increase of COVID-19 in wastewater one week typically meant an increase in new cases the next.

Initially, Boise was among around 600 entities partnering with water testing company BioBot. Pre-pandemic, Biobot was known as a multi-purpose testing and analysis service, with a focus on ailments like norovirus and illicit drugs.

It still does that testing, but pivoted quickly as the pandemic unfolded, helping many municipalities establish wastewater testing for COVID-19 across the country — though Biobot Business Development Manager Jennings Heussner said it's currently partnering with only around 100 companies and communities on COVID-19 testing.

Boise found a better fit for its wastewater analysis using labs at the University of Missouri, and until early November, was sending samples from two sites in Boise by express mail to Missouri three times each week.

Now, the city hand-delivers its samples to Boise State University, and test results arrive sooner showing how much virus is present in local wastewater. The change also saves the city about $1,000 per week, as testing at Boise State is federally funded.

While the data isn't a perfect predictor of cases or hospitalizations, it is shared with federal and local public health officials and local hospital administrators as a way to help prepare for changes in the health of the community.

Falconer said test results informed decisions the city made starting early in the pandemic, and the link between what's in our sewers and the overall health of the public is understood better than before.

"We've created this partnership in a way that is certainly informative during the pandemic, but has the potential to also be useful over time," she said.

Idaho Health and Welfare's Dr. Ball said wastewater scans could be even more important as at-home COVID testing becomes more common, because those test results aren't necessarily going to be reported to public health officials.

Falconer agreed. "It is an imperfect data set in this pandemic, like all of our data. Where it's really beneficial is really filling that gap," she said.

Boise also tests each week for the presence of variants, which still requires sending samples to the University of Missouri. The turn-around time for results is longer, too: 10-14 days. But even with that processing time, wastewater is still likely to be a leading indicator for Idaho.

The Delta variant was first detected in local wastewater before the first case was diagnosed by an individual test. Falconer expects a similar story with Omicron.

Troy Oppie is a reporter and local host of 'All Things Considered' for Boise State Public Radio News. He's also heard Saturday nights on Boise State Public Radio Music's Jazz Conversations.