New RSV vaccine, treatment linked to dramatic fall in baby hospitalizations
arstechnica.com

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Far fewer babies went to the hospital struggling to breathe from RSV, a severe respiratory infection, after the debut of a new vaccine and treatment this season, according to an analysis published today by the Centers for Disease Control and Prevention.

RSV, or respiratory syncytial (sin-SISH-uhl) virus, is the leading cause of hospitalization for infants in the US. An estimated 58,000"80,000 children younger than 5 years old are hospitalized each year. Newborns"babies between 0 and 2 months"are the most at risk of being hospitalized with RSV. The virus circulates seasonally, typically rising in the fall and peaking in the winter, like many other respiratory infections.

But the 2024"2025 season was different"there were two new ways to protect against the infection. One is a maternal vaccine, Pfizer's Abrysvo, which is given to pregnant people when their third trimester aligns with RSV season (generally September through January). Maternal antibodies generated from the vaccination pass to the fetus in the uterus and can protect a newborn in the first few months of life. The other new protection against RSV is a long-acting monoclonal antibody treatment, nirsevimab, which is given to babies under 8 months old as they enter or are born into their first RSV season and may not be protected by maternal antibodies.

For the new study, CDC researchers looked at RSV hospitalization rates across two different RSV surveillance networks of hospitals and medical centers (called RSV-NET and NVSN).

They compared the networks' hospitalization rates in the 2024"2025 RSV season to their respective rates in pre-pandemic seasons between 2018 and 2020.

The analysis found that among newborns (0"2 months), RSV hospitalizations fell 52 percent in RSV-NET and 45 percent in NVSN compared with the rates from the 2018"2020 period.

However, when the researcher excluded data from NVSN's surveillance site in Houston"where the 2024"2035 RSV season started before the vaccine and treatment were rolled out"there was a 71 percent decline in hospitalizations in NVSN. ...