Concentrations of the virus responsible for COVID-19 in wastewater in some Wisconsin cities have been increasing, state health officials confirmed Tuesday, but the significance of that development isn’t clear.

Wastewater virus testing “has been shown to be a leading indicator of cases,” according Elizabeth Goodsitt, a spokeswoman for the state Department of Health Services (DHS), “but more data is needed before we can confirm indications of rising trends.”

About 40% of Wisconsin residents live in areas of the state where wastewater is monitored for changes in the concentration of the SARS-CoV-2 virus in wastewater samples.

Data collected through Wednesday, March 9, has shown increases in the virus concentration in Milwaukee, Green Bay and some smaller communities. DHS has a web page that reports the wastewater virus results from participating wastewater treatment plants around the state.

“These SARS-CoV-2 concentrations are still low, and in a range where there is greater uncertainty in detecting trends,” Goodsitt stated. “However, upward trends identified in larger cities are suggestive of increased community transmission.”

In many other parts of the state, the virus concentration has been declining, the DHS web page indicates.

DHS officials are looking to the wastewater data to provide advance warning of potential new surges in COVID-19 cases around the state.

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