Late-season RSV activity remains elevated in washington

OLYMPIA—The Washington State Department of Health has extended RSV immunizations for infants through April 30. RSV immunizations are usually available from October to March. This extension gives parents more time to protect infants who have not received RSV protection.

“Extending RSV immunizations helps keep babies out of the hospital while disease activity remains high,” said Dr. Tao Sheng Kwan-Gett, State Health Officer, DOH. “If your infant is younger than 8 months or a higher-risk toddler between 8 and 19 months old is not immunized, contact your child’s health care provider soon.”

RSV is a common respiratory virus with mild, cold-like symptoms. Still, it can cause serious illness and hospitalization in infants and older adults. RSV is the leading cause of infant hospitalization in the United States.

In Washington, the 2025–26 RSV season started later than normal, with increased activity beginning in December, which is more than a month later than previous seasons. RSV hospitalization rates among infants under 1 year have been the highest of any age group this season, peaking at approximately 26 per 100,000 in January, with rates still elevated at the end of February.

The delayed start to the Washington RSV season and continued elevated activity into late winter are consistent with national patterns.  

Vaccines for infants provide protection from RSV through monoclonal antibody products, including nirsevimab (Beyfortus) and clesrovimab (Enflonsia). Protection lasts at least five months. 

Children under 8 months should receive nirsevimab during their first RSV season. Children 8–19 months at higher risk, including those who are American Indian or Alaska Native, are recommended to get nirsevimab in their second season.

Monoclonal antibody products can be administered in birthing hospitals prior to discharge and in provider offices. Parents and caregivers should talk with their child’s health care provider about whether RSV protection is recommended for their child.

Learn more about RSV in infants and children at the DOH website, https://tinyurl.com/3aw32juc.