Summary
Washington State Department of Health (DOH) has extended Respiratory Syncytial Virus (RSV) season through April 30, 2026. Please continue to administer nirsevimab or clesrovimab to all eligible patients through April 30.
Current situation
RSV activity in Washington began later than usual this season. Emergency department visits in the state reached the activity threshold in December 2025, compared to October or November in prior seasons. RSV activity and hospitalization rates in young children in Washington remain elevated. The Pierce County Respiratory Illness Dashboard and DOH Respiratory Illness Dashboard provide data at the county and state levels.
Actions requested
Healthcare providers in Washington should:
Identify and immunize
- Assess young children for RSV immunization eligibility and, if eligible, administer nirsevimab or clesrovimab before April 30, 2026.
- All infants under 8 months are eligible if they:
- Have not already received nirsevimab or clesrovimab.
- Are not already protected through maternal RSV vaccination at least 2 weeks before birth.
- Have no contraindications.
- Assess higher-risk infants 8-19 months in their second RSV season and administer nirsevimab if eligible.
Advise
- Counsel families of eligible infants that RSV:
- Remains the leading cause of infant hospitalization in the United States.
- Immunization (monoclonal antibody) is available and recommended through April 30, 2026.
- Patients can find more info about RSV and RSV prevention on DOH’s RSV webpage.
Manage supply
- DOH distribution plan for ordering RSV monoclonal antibodies during the extended season:
- Ordering is limited to birthing hospitals and Tribal clinics.
- Childhood Vaccine Program providers should place orders of RSV monoclonal antibodies using the Immunization Information System (IIS) by March 31, 2026.
- All providers should continue administering any nirsevimab and clesrovimab doses they have on hand to eligible infants through April.
- Providers outside of birthing hospitals and Tribal clinics who need doses should email DOH to facilitate a transfer at WAChildhoodVaccines@DOH.WA.GOV.
- Ordering is limited to birthing hospitals and Tribal clinics.
Background
Respiratory Syncytial Virus (RSV) is a common respiratory virus that usually causes mild upper respiratory illness. However, RSV can cause severe illness leading to hospitalization and even death, particularly in infants and older adults. RSV is the leading cause of infant hospitalization in the United States.
In Washington, the 2025-2026 RSV season had a delayed onset, with elevated activity starting in December 2025, more than a month later than previous seasons. Infants under 1 year have had the highest hospitalization rate of any age group this season. This peaked at approximately 26 per 100,000 in January 2026, with rates still elevated as of late February. The delayed start to the Washington RSV season and continued elevated activity into late winter are consistent with patterns nationally.
Nirsevimab (Beyfortus) and clesrovimab (Enflonsia) are monoclonal antibody products that provide direct protection to infants against RSV. Unlike maternal RSV vaccine, which is administered to pregnant people at 32–36 weeks gestation, RSV monoclonal antibodies are given directly to infants. This allows for greater flexibility to provide protection during seasons with late or prolonged RSV activity.
Resources
Find more info about RSV and RSV immunization:
- Pierce County Respiratory Illness Dashboard, Tacoma-Pierce County Health Department.
- Respiratory Syncytial Virus (RSV), DOH.
- Respiratory Illness Data Dashboard, DOH.
- RSV Prevention, American Academy of Pediatrics.
- RSV Hospitalization Surveillance Network (RSV-NET), Centers for Disease Control and Prevention.
Contact
For questions about RSV immunization product ordering or dose transfers, email the DOH Childhood Vaccine Program at WAChildhoodVaccines@DOH.WA.GOV.
For other questions, please contact:
Tacoma-Pierce County Health Department
Disease Prevention and Management
(253) 649-1412