80% of Infants Protected Against RSV This Season
Most infants born before December were administered nirsevimab, while those whose mothers reached eligible gestational age after October 25 received maternal RSVpreF.
Nearly 80% of infants born during the late 2023 and early 2024 respiratory syncytial virus (RSV) season received protection against the virus, according to a recent study published in JAMA Network.
Most infants born before December were administered nirsevimab, while those whose mothers reached eligible gestational age after October 25 received maternal RSVpreF.
RSVpreF is a vaccine for pregnant women between 32 and 36 weeks of gestation that helps pass immunity to their babies before birth. Approved in August 2023, RSVpreF (Abrysvo) by Pfizer prevents lower respiratory infections caused by RSV and is also used for adults.
Nirsevimab (beyfortus), approved in July 2023, provides targeted RSV protection for infants and young children. This long-acting antibody offers protection to infants under eight months old after birth."
With respiratory illnesses seeing a spike in early 2025, RSV activity stood out as particularly high among young children.
As of January 13, 2025, acute respiratory illnesses remained at high levels across the U.S., with increased emergency department visits for RSV and flu compared to COVID-19 visits, which are currently low.
Access to both nirsevimab and RSVpreF initially faced challenges but showed promise in addressing health disparities. Although there were early shortages of nirsevimab, both options were quickly made available through Kaiser Permanente Northern California (KPNC).
To analyze uptake rates of these new options, researchers examined electronic medical records of infants born to mothers aged 15 to 49 years between October 17, 2023, and March 31, 2024. The mother’s age, race, insurance and prenatal care were observed.
Of the 17,251 infants included in the study, 77.5% received protection from either RSVpreF or nirsevimab. Among them, 33.9% were exposed only to RSVpreF, while 40.9% received only nirsevimab. Roughly 2%, were exposed to both. It’s important to note that 31.1% of infants exposed to both were born preterm, and 24.1% required neonatal intensive care.
When babies were born also made a big difference. For example, 74.5% of infants born from October to November received nirsevimab, while only 52.3% of those born from January to March were exposed to the RSVpreF vaccine through their mothers.
Babies of moms under 25 years were less likely to get protection from RSVpreF compared to babies of moms aged 35 or older. Additionally, protection rates were highest for babies of Asian moms at 86.7% and lowest for babies of Black moms 70.2%.
The study showed both progress and areas that need work. Having two options to protect against RSV helped protect many more infants and might even help reduce some of the inequalities in healthcare.
However, due the study mainly being focused on insured families, it doesn’t fully represent all affected.
Authors suggest it’s crucial to find more options to make these vaccines available to all families.
