A single dose of nirsevimab was effective in reducing visits to the ED for all-cause bronchiolitis by 55.4%, as well as reducing the risk of hospital admission for RSV bronchiolitis by 87.6%.
RT’s Three Key Takeaways:
- Nirsevimab Dramatically Reduces RSV Hospitalizations: A single dose of nirsevimab reduced RSV-related hospital admissions by 87.6% and PICU care needs by over 90% in infants under 6 months, showing strong protection against severe bronchiolitis.
- Real-World Data Validates Effectiveness: The study, conducted across Catalonia, the UK, and Italy, found significant drops in hospitalizations and ER visits only in Catalonia, where nirsevimab was used—highlighting the real-world impact of RSV prevention.
- Best Results in Youngest Infants: The greatest benefit was seen in infants under 6 months, supporting early-life administration; however, larger studies are needed to assess economic feasibility and guide broader policy decisions.
A single dose of the long-acting antibody nirsevimab can halve infant hospitalizations for bronchiolitis, according to data published in Lancet Regional Health – Europe.
Bronchiolitis is an acute viral infection that affects the respiratory system of children primarily in the first six months of life. It is often associated with respiratory syncytial virus infection (in about 3 out of 4 cases) that can cause respiratory failure especially in children under one year of age.
But other viruses can also be the cause, including metapneumovirus, coronavirus, rhinovirus, adenovirus, influenza and parainfluenza viruses. Infection results from transmission primarily by direct contact with infected secretions.
In this study, data collected from 68 Catalan hospitals and 5 hospitals in the UK and Italy show a clear result: in children under 6 months in Catalonia, hospitalizations for bronchiolitis have almost halved compared to the average of previous seasons. Emergency room admissions for the same age group were also significantly reduced. In contrast, no significant reduction emerged in the other European centers where nirsevimab was not administered.
According to data, a dose of nirsevimab was effective in reducing visits to the ED for all-cause bronchiolitis by 55.4% (95% CI: 48.4–61.5%), as well as reducing the risk of hospital admission for RSV bronchiolitis by 87.6% (95% CI: 82.1–91.4%) and need for PICU care for RSV bronchiolitis by 90.1% (95% CI: 76.3–95.9%).
The drug’s effect was less pronounced in older children (between 6 and 23 months), suggesting that the greatest efficacy is concentrated in the first few months of life. The authors also emphasize the need for larger, internationally coordinated studies, not least to assess the economic sustainability of introducing nirsevimab on a large scale.
The study represents an important step in assessing the real effectiveness of new preventive strategies against RSV, comparing for the first time countries with different approaches to its implementation, according to Dr. Danilo Buonsenso, researcher in General and Specialist Paediatrics at the Faculty of Medicine of the Catholic University and paediatrician at the Paediatric Infectious Diseases Unit of the Fondazione Policlinico Gemelli IRCCS.
and was co-ordinated by Dr Danilo Buonsenso, researcher in General and Specialist Paediatrics at the Faculty of Medicine of the Catholic University and pediatrician at the Paediatric Infectious Diseases Unit of the Fondazione Policlinico Gemelli IRCCS.
“Now, for the first time, a real-world study has analyzed the concrete impact of nirsevimab by comparing European countries with different health policies: Catalonia (Spain), where the drug was introduced in 2023-2024, and some areas of the UK and Rome (Italy), where it had not yet been adopted.”
