Reviewed by Shipra Gupta, MD, MS, Children’s Hospital at Montefiore
Bottomline- Nirsevimab protected infants in Western Australia without driving RSV mutations. Genomic and wastewater data showed stable strains, reinforcing its effectiveness while highlighting the need for ongoing surveillance.
In Western Australia’s first season of universal infant nirsevimab prophylaxis (2024), RSV-A predominated (61.8%) over RSV-B (38.2%), with no lineage shifts or resistance mutations detected. Breakthrough infections and ICU cases occurred, mainly with RSV-A, but none showed escape variants. Wastewater data confirmed clinical findings, and nirsevimab coverage (71%) was linked to a 57% drop in infant RSV hospitalizations, providing reassurance of effectiveness without driving resistance, while underscoring the need for ongoing surveillance.
Reference:
Lamichhane, B., et al. (2025). Respiratory Syncytial Virus Strain Evolution and Mutations in Western Australia in the Context of Nirsevimab Prophylaxis. OFID 2025. https://doi.org/10.1093/ofid/ofaf429