Weekly Surveillance Summary

updated:

1/24/2025

Key Points

• Overall acute respiratory illness activity level is High across Chicago, driven mostly by elevated flu activity. Flu activity remains high and COVID-19 activity remains low. RSV activity decreased from high to moderate and is declining across all clinical surveillance indicators.
• The first pediatric RSV death in Chicago of the 2024-25 season was reported this week. 
• ED visits for flu remain significantly elevated across all age groups, as do flu hospital and ICU admissions. ED visits, hospitalizations, and ICU admissions for RSV continue to decrease and are likely past peak for the season. Although ICU admissions for COVID-19 have increased since last week, COVID-19 ED visits have remained similar or decreased across all ages.
• 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 (55%) have been H1N1. Test positivity for RSV has been decreasing over the past 4 weeks. Test positivity for COVID-19 has begun to decrease.
• In the most recent week, 100% of wastewater samples tested positive for all three pathogens. Wastewater concentrations for flu and RSV are high compared to baseline and COVID-19 is low compared to baseline.
• Flu and COVID-19 vaccine coverage across the city remain low. See CDPH’s Mid-Season Seasonal Respiratory Vaccine Coverage Report for more details.
• For information on the national bird flu outbreak, see H5 Bird Flu: Current Situation.