Nirsevimab: Expansion of Respiratory Syncytial Virus Prevention Options in Neonates, Infants, and At-Risk Young Children

Objective: Review available data from clinical trials of nirsevimab for efficacy and safety in the setting of respiratory syncytial virus (RSV) prophylaxis in infants and children, while exploring nirsevimab's role in clinical practice and highlighting continuing questions. Data sources: A literature search of PubMed was conducted utilizing the phrases "nirsevimab" and "medi8897." Additional references were identified through found references. Organizational guidelines, medication labeling, and regulatory organization presentations were utilized. Study selection and data extraction: Relevant clinical trials investigating nirsevimab in infants and children were included as well as other references on pharmacology, pharmacokinetics, and pharmacoeconomics. Data synthesis: Nirsevimab, a once-a-season monoclonal antibody, demonstrated a 79.5% (95% CI, 65.9-87.7; P < 0.00001) lower incidence of RSV-associated medically attended lower respiratory tract infections (MA RSV-associated LRTI) and 77.3% (95% CI, 50.3-89.7; P = 0.0002) reduction in hospitalizations for RSV-associated MA-LRTI across 2 placebo-controlled studies. Nirsevimab demonstrated comparable safety to placebo with minor dermatologic reactions being the most common adverse event (0.9% vs 0.6%). Relevance to patient care and clinical practice in comparison with existing agents: Nirsevimab was approved by the US Food and Drug Administration, and recommended by the Advisory Committee on Immunization Practices and American Academy of Pediatrics for broad administration to infants entering their first RSV season and at risk patients during their second RSV season. Questions remain over efficacy in infants born < 29-week gestation and other economical considerations. Conclusions: Nirsevimab demonstrated clinical efficacy in reducing RSV-associated MA-LRTI and RSV-associated hospitalizations in infants and was well tolerated.