RSV Cases Remain Elevated in Chicago, Marking an Unusual Late-Season Surge

Respiratory syncytial virus (RSV) activity remains higher than usual in Chicago, prompting health officials to urge continued vigilance even as spring approaches. While RSV typically peaks during the winter months alongside influenza and COVID-19, its persistence into mid-March is considered atypical.

What is RSV?

Respiratory syncytial virus (RSV) is a common respiratory virus that infects the nose, throat, and lungs. Symptoms often mimic those of a common cold or other respiratory illnesses, making diagnosis challenging. RSV spreads through direct contact with the virus, such as droplets from coughs or sneezes, or by touching contaminated surfaces and then touching the face before washing hands.

Current RSV Activity in Chicago

As of March 13, 2026, the Chicago Department of Public Health (CDPH) reports that RSV activity has increased from moderate to high. This is higher than typically observed at this time of year compared to previous seasons. Emergency department (ED) visits and hospitalizations for RSV remain elevated, particularly among children aged 0-4 years, and are more than three times higher compared to the same week last year.

So far this season, two RSV-associated pediatric deaths have been reported in Chicago. Wastewater surveillance also indicates “very high” concentrations of RSV.

Statewide, RSV activity is currently rated as moderate, according to the Illinois Department of Public Health.

Symptoms of RSV

Symptoms of RSV infection typically appear within 4 to 6 days of exposure and can include:

• Runny nose
• Congestion
• Decreased appetite
• Coughing
• Sneezing
• Fever
• Wheezing

In very young infants, symptoms may be limited to irritability, decreased activity, and breathing difficulties.

RSV Immunization and Prevention

Recent vaccines and monoclonal antibodies are available to help protect against severe RSV illness.

• RSV Vaccines for Adults: Vaccines are recommended for adults ages 50 years and older. These are not currently annual vaccines.
• Maternal RSV Vaccine: Pfizer’s Abrysvo can be given during pregnancy (weeks 32-36, September-January) to help protect the baby after birth.
• RSV Antibodies for Infants: Nirsevimab and Clesrovimab are monoclonal antibodies given to infants after birth.

Approximately 58% of Chicago infants born during the 2023-2024 year have received some form of RSV protection through maternal vaccination or monoclonal antibody administration, a significant increase from 17% the previous year.

Why is RSV Still Circulating?

Experts are unsure why RSV activity remains elevated so late into the season. Potential factors include colder weather patterns encouraging indoor gatherings or a delayed start to the RSV season.

Protecting Your Family

Health officials recommend continued vigilance, including practicing good hygiene such as frequent handwashing, avoiding close contact with sick individuals, and considering mask-wearing and covering coughs. The CDPH is also considering recommendations for continued infant immunization beyond March.