Nirsevimab Shows High Effectiveness Against RSV in Kids
A new study shows the immunization reduces RSV-related hospitalizations by 75% for high-risk children in their second season.
Updated on Oct. 22, 2026 in Children’s Health
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A study conducted between November 2024 and March 2026 found that nirsevimab immunizations were 75% effective at preventing RSV-associated hospitalizations in high-risk children during their second season. This real-world evidence supports the American Academy of Pediatrics' decision to expand eligibility for second-season RSV immunization.
Why it matters
Understanding how nirsevimab performs in the second RSV season is critical for clinicians and caregivers managing high-risk children, as it informs decisions about preventive immunization. The study provides essential data to guide immunization strategies for children who remain at elevated risk beyond their first year of life.
A hospital-based case-control study of 231 high-risk children across 26 U.S. hospitals found 75% effectiveness for nirsevimab against RSV-associated hospitalizations. The study, conducted during the 2024-2025 and 2025-2026 seasons, noted effectiveness reached 86% when administered within 60 days of symptom onset.
The players
American Academy of Pediatrics
A professional organization of pediatricians that sets clinical guidelines for child health and recommends immunization criteria.
The details
Researchers matched hospitalized children with respiratory symptoms who tested positive for RSV against those who tested negative to calculate relative effectiveness. Nirsevimab works as a long-acting monoclonal antibody that provides passive immunity by neutralizing the RSV virus directly. The data showed that 20% of vaccinated patients tested positive for RSV, compared to 42% in the non-immunized group, demonstrating the impact of the immunization in reducing severe disease outcomes.
Timeline
November 2024 to March 2026: The study duration covering two RSV seasons.
Health Landscape
This study updates the effectiveness figures previously established by the American Academy of Pediatrics RSV immunization eligibility criteria. It marks a critical step in refining preventive strategies for the 2% to 4% of the pediatric population identified as high-risk.
Caregivers of high-risk children should consult their pediatrician about updated RSV immunization eligibility for the current season. Discuss whether your child meets the criteria for second-season protection and how this preventive approach fits into their overall care plan.
The takeaway
Nirsevimab demonstrates significant effectiveness in preventing RSV-related hospitalizations for high-risk children entering their second season. Caregivers should track their child's health history and discuss updated immunization eligibility with a primary care physician before the start of the RSV season.
Further reading
For more on protective measures against common respiratory infections, visit the Children’s Health section.
Source note: This article includes information reported by MedPage Today.
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