Key Points, updated 8/29/2025

• Overall acute respiratory illness activity level in Chicago remains Minimal, but COVID-19 activity continues to rise. COVID-19 lab positivity, hospital visits emergency department visits, and wastewater activity have been increasing. National data also suggest epidemic growth in Illinois and across the country.
• ED visits, hospitalizations, and ICU admissions for flu, RSV and COVID-19 remain low across all age groups. Hospital admissions for COVID-19 remain highest among older adults. ED visits for COVID-19 have continued to increase since August, especially among children under 4.
• COVID-19 test positivity continues to increase and is currently 5.2%. This is the highest level since January 2025. Test positivity rates for flu and RSV are unchanged and remain low.
• Overall wastewater concentrations for COVID-19 have decreased from Very High to Low. The previous High reading was attributed to a concentration detected in a sewershed serving the Loop and near South Side. The detection in that sewershed has since decreased from Very High to Moderate. RSV concentrations remain Minimal. Flu A concentrations remain Minimal and flu B concentrations decreased from Low to Minimal.
• The CDC Center for Forecasting & Outbreak Analytics has released the 2025-2026 Respiratory Disease Season Outlook. Their scenario modeling indicates that this season will likely have a similar combined number of peak hospitalizations due to COVID-19, influenza, and RSV as last season.
• Parvovirus B19 activity has decreased in Chicago but remains elevated compared to previous years. For more information and guidance see the July 10 Health Alert.