Key Points, updated 5/16/2025

• Overall acute respiratory illness activity level in Chicago has decreased from Low to Minimal. Flu activity remains Low; COVID-19 and RSV activity remain Minimal.  
• ED visits, hospitalizations, and ICU admissions for flu, RSV, and COVID-19 remain low across all age groups.
• The percentage of specimens that tested positive for flu continues to decline as we approach the end of the influenza surveillance season. Of all influenza positive specimens last week, nearly all (83%) were associated with flu B. Test positivity for COVID-19 and RSV remain low. 
• The percentage of specimens that tested positive for rhinovirus/enterovirus has been increasing since March, consistent with past years’ seasonal trends. 
• Overall wastewater concentrations for RSV and COVID-19 have decreased from low to minimal. Flu A and Flu B concentrations have decreased from moderate to low. 
• The CDC has issued interim estimates of 2024-25 Seasonal Influenza Vaccine Effectiveness (VE) and 2024-25 COVID-19 VE, which suggest that this season’s influenza and COVID-19 vaccines were effective in preventing medically-attended illness, including hospitalization, in the US. 
• 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 the CDPH H5N1 Bird Flu webpage and the CDPH HAN: Flu Page for clinicians.