Weekly Surveillance Summary

updated:

1/17/2025

Key Points

• Overall acute respiratory illness activity level is MODERATE across Chicago. Flu levels remain high while COVID-19 levels have decreased from moderate to low.  RSV activity decreased from very high to high and is declining across all clinical surveillance indicators.   
• ED visits for flu remain significantly elevated across all age groups, as do flu hospital and ICU admissions. Most flu-related ICU admissions have been among people ≥65 years. ED visits, hospitalizations, and ICU admissions for RSV have decreased and are likely past peak for the season. ED visits for COVID-19 have remained similar or decreased across all ages except for children 0-4 years. ICU admissions for COVID-19 have decreased since last week.  
• The percentage of specimens that tested positive for flu remains high. Almost all (99%) typed flu specimens are flu A; among those subtyped, about half (54%) have been H1N1. Test positivity for RSV remains elevated but has been decreasing over the past 3 weeks. Test positivity for COVID-19 continues to increase. 
• Wastewater concentrations for flu, COVID, and RSV have all increased and levels for flu and RSV are high compared to baseline. 
• Flu and COVID-19 vaccine coverage across the city remain low. See CDPH’s Mid-Season Seasonal Respiratory Vaccine Coverage Report released on 1/13/2025 for more details.
• For information on the national bird flu outbreak, see H5 Bird Flu: Current Situation.