Immunizations and the late RSV season: an extra month that could keep babies out of the hospital

In Olympia, the waiting-room chairs fill with parents shifting diaper bags on their knees, listening for their child’s name and watching the door that leads to exam rooms. The talk is practical—coughs, day care, sleep—yet it lands on the same urgent decision: immunizations for RSV protection, now extended because the virus is still circulating at elevated levels later than usual.

Why are states extending Immunizations for RSV protection beyond the usual season?

Health officials in Washington state say the RSV season started later than normal and remains active into late winter. The Washington State Department of Health has extended the availability of RSV immunizations for infants through April 30, even though they are typically available between October and March. State the 2025–26 RSV season in Washington began with increased activity in December—more than a month later than previous seasons—and rates have stayed elevated as of late February.

In Montana, the Montana Department of Public Health and Human Services is advising health care providers to continue offering preventive immunizations against RSV for infants and young children through April 30, 2026. RSV activity has been rising and spreading later than usual, and it determined an additional month is needed to help protect infants from severe complications.

What is happening to infants during this delayed RSV season?

In Washington, health officials say infants have been hit hardest. RSV hospitalization rates among infants younger than 1 year have been the highest of any age group this season, peaking at about 26 per 100, 000 in January, with rates still elevated as of late February. The Washington State Department of Health also said RSV is the leading cause of infant hospitalization in the United States, and noted the delayed start and continued elevated activity into late winter are consistent with national patterns.

Dr. Tao Sheng Kwan-Gett, the state health officer at the Washington State Department of Health, framed the extension as a way to prevent severe outcomes while activity remains high.

“Our hope is that by extending the administration period for RSV immunizations, we can continue to keep babies out of the hospital while disease activity is still high, ” Dr. Kwan-Gett said.

He urged families with eligible children to move quickly: “If you have an infant younger than 8 months or a higher-risk toddler between 8 and 19 months old who hasn’t gotten immunized against RSV this season, talk to your child’s health care provider as soon as you can about RSV protection. ”

In Montana, Dr. Doug Harrington, State Medical Officer at the Montana Department of Public Health and Human Services, said the extension is meant to buy time during a period of heightened activity.

“Montana’s RSV activity is still increasing, ” Dr. Harrington said. “Extending access to RSV preventive antibodies through April gives families and providers more time to get eligible infants covered during this heightened period of activity. We encourage parents to talk with their child’s provider as soon as possible. ”

What do specialists say about why the season is late—and how RSV spreads?

In Washington, Dr. Scott Lindquist, medical state epidemiologist for the state of Washington, said the timing shift has been notable and not fully understood.

“What has happened this year with the RSV season is it appears to be about a month-to-two-months later than usual, ” Lindquist said, adding that the extension is tied to continued activity past March.

He said the reason for the delayed timing is unclear. “No one really understands this, ” he said.

Dr. Lindquist also described why infants and toddlers can become seriously ill: the virus can affect their airways and cause significant breathing problems, and RSV can arrive in what he called “really intense bursts during the respiratory season. ” He said some children are more prone to severe illness, including younger children and those with underlying lung conditions.

On prevention, he emphasized everyday habits alongside clinical protection. “To be honest with you, the most common spread of RSV is your fingers, ” Dr. Lindquist said. He urged “respiratory etiquette, ” including handwashing, covering coughs and staying home when sick, especially from work, school or day care.

What protection is being offered, who is eligible, and what should families do now?

For infants, Washington health RSV immunization is provided through monoclonal antibody products such as nirsevimab (Beyfortus) and clesrovimab (Enflonsia), which provide antibodies to help protect young children from RSV. The Washington State Department of Health said protection lasts at least five months, and it recommends that all children younger than 8 months receive nirsevimab during their first RSV season.

In Montana, the Department of Public Health and Human Services guidance advises providers to continue offering RSV immunization through April 30 for infants younger than 8 months old who have not yet been immunized this season and meet eligibility criteria, and for children ages 8–19 months who are in their second RSV season and are at increased risk for severe disease. The agency also noted that infants should ideally receive the dose in the hospital after birth or within their first week of life, though it can be administered during any health care visit.

The immediate steps health officials stress are straightforward: caregivers should consult a pediatrician or child’s health care provider to determine eligibility and timing while the window remains open. For many families, that turns a lingering worry into a calendar decision—one more appointment, one more chance to reduce the risk of a hospital visit during a season that refuses to end on schedule.

Back in the clinic corridor, the same small moment repeats: a parent pulls up a sleeve, a nurse checks a chart, and a baby fusses at the unfamiliar cold of a stethoscope. In a year when the virus arrived late and stayed high, the extra time for immunizations is being treated by health officials as a practical tool—meant to help families meet the season where it is, not where it was supposed to be.