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Wastewater suggests UArizona could be past Omicron peak

UArizona researcher Nick Childress collects a wastewater sample to be tested for concentration of coronavirus.
Posted at 10:18 PM, Jan 18, 2022
and last updated 2022-01-19 00:18:39-05

TUCSON, Ariz. (KGUN) — It’s a dirty job, but University of Arizona researchers say it’s a crucial one in the fight against COVID-19.

A team from the university’s Water & Energy Sustainable Technology (WEST) Center collects wastewater from 18 different buildings on campus six days a week—while also taking a sample from Tucson once per week—in order to test the sewage water for the virus.

“When someone is infected, they start shedding Sars CoV-2 immediately. And so you can detect the virus in the wastewater 8-10 days prior to visible symptoms of an infected individual,” WEST Center director and UArizona professor Dr. Ian Pepper explained.

According to Pepper, the current Omicron surge is evident when testing the sewage.

“I can tell you that two weeks ago the levels were the highest we’ve ever seen,” Pepper said. “On December 22nd we had 100,000 gene copies per liter. By January 5th, it was 10 million.”

Pepper reports the virus levels have dropped recently, however. He says they are at roughly one million gene copies per liter now.

That drop signals the community could potentially be past the peak of infections.

“Remember, this is a leading indicator,” Pepper said. “So the fact that the wastewater levels are decreasing somewhat may indicate that we’ve seen the worst. Hopefully, that is correct.”

Pepper points out that even after a decrease, virus levels are still “much higher” than they were in the fall.

He also says wastewater data suggests there was more COVID spread going on in the fall than students realized.

“I believe there were a lot of asymptomatic cases,” Pepper said. “The concentrations, actually, in the wastewater were higher or as high as the previous year, but the number of cases were far less. So that means you’re seeing asymptomatic cases which are frequently not detected or counted.”

UArizona plans to continue testing the wastewater through at least June 30.

Pepper says the science of wastewater-based epidemiology (WBE) is likely here to stay, however, with other cities and countries around the world employing it to be warned about COVID spread before symptoms appear and cases rise.