Abstract Respiratory syncytial virus (RSV) transmission between 2020–2025 was impacted by COVID-19 related public health measures, resulting in unprecedented genomic bottlenecks, and post-pandemic surges in clinical cases. We performed whole-genome sequencing of 100 infant RSV cases in Sydney during the 2024 winter season. Phylogenetic analysis revealed a marked rebound in genomic diversity compared with prior seasons, driven by multiple international lineage introductions. No known therapeutic-resistance mutations were detected. These findings provide a pre-intervention baseline for monitoring RSV evolution under emerging therapeutic selection pressures in Australia, with the national rollout of the recently approved maternal vaccine (Abrysvo) and monoclonal antibody (nirsevimab) through the RSV Mother and Infant Protection Program commencing in 2025.
Herkes et al. (2026) studied this question.