First real-world data on universal respiratory syncytial virus prophylaxis with Nirsevimab in infants

Respiratory syncytial virus (RSV) predominantly affects young children, with a peak incidence in temperate regions of the northern hemisphere from October to May. Children under 24 months of age are particularly vulnerable because of the immaturity of their lungs and immune systems, which often leads to severe respiratory infections. The World Health Organization (WHO) recognizes RSV as a global health priority. Recently, Nirsevimab, a long-acting mAb, was authorised to prevent RSV in infants. Our narrative review brings together the field effectiveness data of Nirsevimab available in the literature, highlighting the strengths and weaknesses of the published studies and the prevention opportunities represented by the new preparation. All studies reviewed provide evidence for the effectiveness of immunisation with Nirsevimab in real-world settings, beyond the controlled conditions of clinical trials, and highlight its safety and feasibility. Nirsevimab significantly reduces RSV hospitalisations and ICU admissions. High coverage and high efficacy of immunisation have been reported, although supply issues and variability in studies present challenges. Continued research and surveillance are critical to understanding the long-term effectiveness of Nirsevimab. Overall, available data provide valuable insights into the efficacy, safety, and impact of immunisation with Nirsevimab in preventing severe RSV infections in infants, highlighting its potential to reduce the burden of RSV-related hospitalisations and improve paediatric health outcomes.