The Washington State Department of Health has extended its RSV season designation through April 30, 2026, directing healthcare providers to continue administering RSV monoclonal antibodies to eligible infants. The extension applies to the drugs nirsevimab and clesrovimab.
This season's RSV activity started later than usual in Washington. Emergency department visits reached the state's activity threshold in December 2025, compared to October or November in previous years. Hospitalization rates among young children remain elevated statewide.
All infants under 8 months are eligible for immunization if they have not already received nirsevimab or clesrovimab, were not protected through maternal RSV vaccination at least two weeks before birth, and have no contraindications. Higher-risk infants between 8 and 19 months in their second RSV season may also be eligible for nirsevimab.
RSV is the leading cause of infant hospitalization in the United States. Healthcare providers are asked to assess patients for eligibility and counsel families on the availability of immunization through April 30.