Nirsevimab program cuts RSV hospitalizations across 2 seasons

Respiratory syncytial virus (RSV)-related hospitalizations are significantly reduced by an immunization program using nirsevimab (Beyfortus; AstraZeneca), according to a recent study published in The Lancet Infectious Diseases.¹

This was the first real-world population study to assess outcomes following a universal nirsevimab program across 2 consecutive RSV seasons. The data highlighted significant reductions in RSV-related lower respiratory tract infection (LRTI) hospitalizations in both the first and second RSV seasons of 85.9% and 55.3%, respectively.

"This universal RSV immunization program with Beyfortus showed decreased RSV-related hospitalizations and outpatient illness burden during the first season, with persistent impact seen on RSV hospitalizations through the second season,” said Federico Martinón-Torres, MD, PhD, principal investigator and head of pediatrics at Santiago University Hospital.

High coverage and reductions in outpatient burden

Coverage was reported in 94.4% of the cohort. Alongside the significant reductions in LRTI hospitalizations, the study highlighted significant reductions in primary care consultations during the first RSV season. These included:

• A 30.8% decline in first consultations for acute bronchitis or bronchiolitis
• A 33.4% decline in consultations for LRTIs
• A 27.7% decline in consultations for wheezing or asthma

Rehospitalization rates were also significantly reduced during the second RSV season among infants with prior hospitalization linked to RSV, with a decline of 78.2%. For LRTI hospitalizations, this decline was 62.4%. According to investigators, this indicates lasting benefits to respiratory health from early protection against RSV damage to the lungs.

Indications, administration, and real-world experience

The immunization has been approved for children aged up to 24 months. This population is vulnerable to severe RSV infection throughout their second RSV season. Nirsevimab was designed to prevent RSV-related LRTI in these patients, with administration timed to coincide with the RSV season.

Nirsevimab is administered to infants as a single dose, leading to rapid protection without needing to activate the immune system. It has an extended half-life of 71 days and has proven efficacy across 50 real-world studies including more than 400,000 infants. Over 11 million infants have been immunized by nirsevimab since its launch.

“These results offer compelling population-based data to inform infant immunization strategies and economic evaluation models,” said Martinón-Torres.

Broader implications for pediatric respiratory health

RSV vaccination may also have downstream benefits, as discussed by Octavio Ramilo, MD, chair of the Department of Infectious Diseases at St. Jude Children’s Research Hospital, in an interview with Contemporary Pediatrics.² This includes potentially reducing the global burden of pneumonia.

Ramilo highlighted RSV as 1 of 2 primary drivers of childhood pneumonia worldwide, which is currently the top priority for pediatric health agencies. Preventing RSV early in life through monoclonal and maternal vaccines has the potential to reduce associated morbidity and mortality. It may also lead to other health benefits such as reduced ear infections.

Overall antibiotic use may also be reduced by RSV vaccination. According to Ramilo, preventive measures such as nirsevimab are likely to be well received by families when the benefits are clearly explained.

“Pregnant women will do whatever it takes to protect the baby,” said Ramilo. “That’s sometimes an easier conversation, one in these very small babies than other vaccines we give to kids...[but] families want to protect the babies.”

Reference

1. Press Release: Beyfortus study published in The Lancet Infectious Diseases shows benefit for infants beyond first RSV season. Sanofi Winthrop Industries. February 16, 2026. Accessed February 16, 2026. https://www.globenewswire.com/news-release/2026/02/16/3238527/0/en/Press-Release-Beyfortus-study-published-in-The-Lancet-Infectious-Diseases-shows-benefit-for-infants-beyond-first-RSV-season.html
2. Ramilo O. Potential downstream benefits of RSV preventive measures, with Octavio Ramilo, MD. Contemporary Pediatrics. June 20, 2025. February 16, 2026. https://www.contemporarypediatrics.com/view/potential-downstream-benefits-of-rsv-preventive-measures-with-octavio-ramilo-md