Seasonality and regional variation of respiratory syncytial virus–associated hospital admissions in northern Western Australia, 2012-2023

OBJECTIVE: The aim of this study was to compare the seasonality of respiratory syncytial virus-associated hospital admissions in northern tropical Western Australia (Kimberley and Pilbara regions) to southern temperate Western Australia. METHODS: version, Australian modification diagnostic coding to identify respiratory syncytial virus-associated hospital admissions from 2012 to 2023 across Western Australia. RESULTS: We showed that respiratory syncytial virus-associated hospital admissions in southern temperate Western Australia followed a winter seasonality with the peak of the season typically in July to August. The Pilbara also generally followed a winter seasonality of respiratory syncytial virus-associated hospital admission rates. However, the Pilbara showed greater yearly variability and a longer duration of activity than southern temperate Western Australia. The Kimberley showed both higher rates of respiratory syncytial virus-associated hospital admissions and no clear seasonal patterns, with monthly and yearly variation compared to southern temperate Western Australia. CONCLUSIONS: Seasonal variation of respiratory syncytial virus-associated hospital admissions is seen in both the Kimberley and Pilbara regions compared to southern temperate Western Australia. IMPLICATIONS FOR PUBLIC HEALTH: The distinct seasonal variation in the northern regions of Western Australia should be considered when planning and implementing respiratory syncytial virus immunisation programs.