Key Points, updated 8/22/2025

• Overall acute respiratory illness activity level in Chicago remains Minimal, but COVID-19 activity continues to rise. COVID-19 lab positivity, hospital admissions, and wastewater activity have all 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, especially among older adults, have been increasing since the beginning of August. 
• COVID-19 test positivity continues to increase and is currently 5.5%. 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 increased from Minimal to Very High; this increase was primarily driven by a high viral concentration detected in a sewershed serving the Loop and near South Side. RSV concentrations remain Minimal. Flu A concentrations decreased from Low to Minimal and Flu B concentrations increased from Minimal to Low.
• Parvovirus B19 activity has been increasing in Chicago and across the US. For information and guidance, see the July 10 Health Alert.