Respiratory Syncytial Virus (RSV) Season Extension Update and Guidelines March 19, 2026
JB Pritzker, Governor Sameer Vohra, MD, JD, MA, Director
Respiratory Syncytial Virus (RSV) Season Extension Update and Guidelines
March 19, 2026
Summary and Action Items
RSV activity remains elevated in Illinois; therefore, infant RSV immunization has been extended through the end of April 2026.
1.) As of the week ending March 7, 2026, RSV percent positivity was 8.0%, remaining well above the 3% threshold for the RSV season. Hospitalizations and emergency department visits for RSV also remain elevated. This indicates a delayed end of the RSV season at least through April.
2.) Clinicians should actively recommend and offer RSV immunization to all infants under the age of 8 months who lack maternal RSV vaccine protection entering or in their first RSV season and to children ages 8 months through 19 months who are at increased risk for severe RSV disease and in their second RSV season. Certain infants may receive RSV immunization regardless of maternal vaccination status in specific situations described below. Immunization should continue through the end of April 2026.
3.) All adults ages 75 years and older, as well as adults ages 50 years through 74 years at increased risk of severe RSV disease, should receive RSV vaccination if they have not previously been vaccinated.
4.) If based on clinical judgment there would be benefit from maternal vaccination (e.g., it is unlikely or uncertain that the infant will receive RSV immunization at birth), it is acceptable to continue to vaccinate pregnant individuals at 32 through 36 weeks of pregnancy at this time through the end of March 2026.
Background
RSV activity remains elevated in Illinois. As of the week ending March 7, 2026, percent positivity was 8.0%, remaining well above the commonly considered 3% threshold for the RSV season. Hospitalizations and emergency department visits for RSV also remain elevated. This indicates a delayed end of the RSV season at least through April.
In Illinois this season, there have been 2 reported pediatric RSV-related deaths. In addition, the state’s death registry has identified 8 adults, all of whom were over age 75 years, with RSV listed as a cause of death. The number of RSV-related deaths in Illinois may possibly be higher as adult RSV deaths are not reportable and are likely under-reported on death certificates.
Based on data for individuals with immunization records in the state immunization information system (I‑CARE), only 33.6% of infants under 8 months of age had documented receipt of nirsevimab last season. Similarly, among adults ages 75 years and older with records in I‑CARE, only 30.6% had documentation of receiving an RSV vaccine last season. (Note: These percentages reflect only individuals whose vaccination information is submitted to I‑CARE and may not represent overall population coverage.) The persistently elevated RSV activity in Illinois and reported RSV-related deaths underscore the ongoing risk of infection and importance of immunization.
See the Illinois Seasonal Respiratory Illness Dashboard for the most current data.
Prevention Through Immunization
Infant/Child Immunization
Clinicians should provide RSV immunization for all eligible infants and children. Administration of RSV antibody is typically recommended October through March. However, at this time, given a delayed end to this RSV season, clinicians should continue to actively recommend and offer RSV immunization to eligible infants through the end of April 2026.
Infant immunization during their first RSV season
The optimal timing for infant RSV antibody administration for those born during RSV season is within the infant’s first week of life, ideally during the birth hospitalization.
There are two monoclonal antibody products available: nirsevimab and clesrovimab. Palivizumab is no longer recommended.
For infants younger than 8 months of age, an RSV antibody (nirsevimab or clesrovimb) is recommended for those who are born during or are entering their first RSV season if:
• The mother did not receive RSV vaccine during pregnancy, or
• The mother’s RSV vaccination status is unknown, or
• The infant was born within 14 days of maternal RSV vaccination.
Situations in which infant immunization may be considered regardless of maternal vaccination status
Nirsevimab or clesrovimab may be considered for infants born to vaccinated mothers in circumstances when, based on the clinical judgment of the health care provider, the potential incremental benefit of administration is warranted.
These situations include but are not limited to the following:
• Infants born to mothers who might not have mounted an adequate immune response to vaccination (e.g., persons with immunocompromising conditions) or who have conditions associated with reduced transplacental antibody transfer (e.g., persons living with HIV infection)
• Infants who might have experienced loss of maternal antibodies, such as those who have undergone cardiopulmonary bypass or extracorporeal membrane oxygenation
• Infants with substantially increased risk for severe RSV disease (e.g., hemodynamically significant congenital heart disease, or intensive care admission requiring oxygen at hospital discharge)
Children recommended to receive immunization during their second RSV season
For some children ages 8 months to 19 months who are at increased risk for severe RSV disease and entering their second RSV season, nirsevimab is recommended. Clesrovimab is not approved for this indication.
The following children ages 8 months through 19 months are recommended to get nirsevimab shortly before or as early as possible during their second RSV season:
• Children with chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the second RSV season
• Children with severe immunocompromise
• Children with cystic fibrosis who have either 1) manifestations of severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable), or 2) weight-for-length <10th percentile
• American Indian or Alaska Native children
Maternal Vaccination
RSV vaccination is recommended for pregnant people during weeks 32 through 36 weeks of pregnancy to protect their infants from severe RSV disease. The vaccine should be ideally administered starting 1-2 months before the anticipated start of the RSV season through 2-3 months before the anticipated end of the RSV season, which is typically from September through January for most of the continental United States. However, given the delayed end of the current RSV season in Illinois, if based on clinical judgment there would be benefit from maternal vaccination (e.g., it is unlikely or uncertain that the infant will receive RSV immunization at birth), it is acceptable to vaccinate pregnant individuals at 32-36 weeks of pregnancy at this time through the end of March 2026.
If a pregnant person has received a maternal RSV vaccine during any previous pregnancy, another dose is not recommended at this time, and immunization of the infant should be ensured. Pfizer’s Abrysvo is the only RSV vaccine currently approved for use during pregnancy.
Adult Vaccination
RSV vaccination is recommended for all adults ages 75 years and older and for adults ages 50 years through 74 years at increased risk of severe RSV disease. Eligible adults without prior RSV vaccination may be vaccinated at any time of year, but vaccination will have the most benefit it administered in late summer or early fall. The RSV vaccine is currently not an annual vaccine, meaning eligible adults only need a single dose.
For a list of conditions that increase the risk of severe RSV, see CDC RSV Vaccine Guidance for Adults.
See CDC Clinical Guidance for RSV Immunizations and Vaccines for additional guidance.
Health Insurance Coverage Implications and the Vaccines for Children Program
The extension of the RSV immunization season based on local RSV seasonality falls within current ACIP/CDC recommendations that clinicians should follow guidance from public health authorities or regional medical centers on timing of administration based on local RSV seasonality. In addition, the federal Vaccines for Children Program has extended ordering for RSV monoclonal antibody immunizations until April 30, 2026.
For more information on state-regulated insurance plan coverage of immunizations, see the Illinois Department of Insurance Immunization/Vaccination Coverage FAQs.
Testing and Reporting
With the exception of laboratories enrolled as a virologic respiratory sentinel site, routine testing performed for inpatient and outpatient clinical care, including PCR testing, should be obtained at clinical and hospital laboratories.
Providers should report the following to the local health department:
• Pediatric death due to RSV
o These cases are reportable as soon as possible, but within three days.
• Intensive care unit (ICU) hospitalizations with RSV
o All ICU admissions for RSV should be reported, even if it is not the specific reason for ICU admission.
o These cases are reportable as soon as possible, but within three days.
• Outbreaks of acute respiratory illness in a congregate setting (e.g., skilled nursing facilities, assisted living facilities)
o See IDPH guidance for acute respiratory illness outbreak management in skilled nursing facilities and community congregate settings.
See IDPH guidance on respiratory testing and reporting for additional reference.
Infection Control and Other Preventive Measures
In addition to immunization, the following core and additional prevention strategies are recommended for the general public with viral respiratory illnesses, including RSV, influenza, COVID-19, and other etiologies, whether tested for or not. These should be included in patient education:
• Practice good respiratory and hand hygiene.
• If sick, isolate at home and away from others until at least 24 hours of being fever-free without use of fever-reducing medication and symptoms are improving
• Once able to leave home, wear a well-fitting mask for at least the next 5 days.
See the IDPH Infectious Respiratory Disease Guidance page for infection control guidance specific to health care settings and health care personnel, long-term care facilities, community congregate settings, correctional facilities, schools, and non-health care workplaces.
IDPH has issued guidance for work exclusion and return-to-work conditions for healthcare personnel with acute viral respiratory infections.
Resources
IDPH Immunization Guidelines
IDPH Infectious Respiratory Disease Guidance
IDPH Seasonal Respiratory Illness Dashboard
CDC Clinical Guidance for RSV Immunizations and Vaccines
CDC Respiratory Virus Guidance: What to Do When You Are Sick
Target Audience
Local Health Departments, Health Care Professionals, Physicians, Pharmacists, Infectious Disease Staff, Hospital/Clinic Administrators, FQHC Administrators, Long Term Care Facilities, and Regional Health Offices.
Date Issued
March 19, 2026
