Wastewater sampling has been a key early-warning tool for detecting spikes in the spread of COVID-19, and now Illinois is making its data available to the public through an interactive online dashboard.

The Illinois Department of Public Health (IDPH) and the Discovery Partners Institute (DPI) announced Tuesday a new website that tracks the levels of COVID-19 in wastewater samples voluntarily collected at 75 sites across the state, including Chicago. The data is searchable by site and presented in easy-to-read graphs.

“This data is now going to be available to researchers and the public alike, giving everyone as accurate a picture as possible for the pandemic,” said Bill Jackson, executive director of DPI, in a statement. “This is a game-changer in terms of transparency and public health awareness.”

IDPH contracted with Discovery Partners Institute at the University of Illinois-Chicago to develop the Illinois Wastewater Surveillance System, which received more than $6.5 million from the federal government to participate in the National Wastewater Surveillance System, a program that’s funded through September 2025.

Infected people shed genetic material from the virus in their waste, where it eventually shows up in the raw sewage piped into purification facilities. Samples are collected from participating facilities twice a week and taken to a lab at the University of Illinois-Chicago for analysis and then to Argonne National Laboratory for genetic sequencing to identify virus variants. Northwestern University is also assisting with data modeling and analytics.

With most people having switched to at-home tests for COVID-19 and not reporting results to public health officials, wastewater data has become an increasingly reliable source of information for public health authorities on the virus' spread. Wastewater samples, for example, showed evidence of the Omicron variants before they were reported in infected individuals, according to the Centers for Disease Control and Prevention. 

While wastewater surveillance can detect changes in the amount of virus in an area, it can’t say how many people have COVID-19 at a particular time. The information is considered in tandem with COVID-19-related hospitalizations, ICU admissions and deaths, among other metrics, to make public health decisions, officials previously told WTTW News.

The DPI team recently began screening sewage samples for influenza A and B for IDPH, and the goal is to share these results on the dashboard, too.

Some tips from health officials for those using the dashboard:

— Wastewater surveillance data is "noisy," meaning it is highly variable. For this reason, the focus is on trends over time, specifically significant increases.

— This same variability means data shouldn't be compared between collection sites. 

Kristen Thometz contributed to this report.

Contact Patty Wetli: @pattywetli | (773) 509-5623 |  [email protected]