Understanding the epidemiological shifts of respiratory syncytial virus (RSV) is essential to inform public health interventions, particularly given its increased burden on healthcare systems post-COVID-19 pandemic. This study aimed to examine age-specific trends and seasonal variations in RSV incidence, considering the recent introduction of a newborn RSV immunisation programme in Ireland.

A surveillance time series study analysing routinely collected RSV notification data.

National-level weekly RSV notifications collected by the Health Service Executive-Health Protection Surveillance Centre in Ireland from 2012 to 2024.

Infants (

Annual trends in RSV epidemiology with special reference to the pre- and post-COVID-19 winter surges, and the time lag in age-related transmission to peak incidence among the various age groups. Data were analysed to evaluate incidence rates, peak timing, age-related transmission trends and lag times before and after the COVID-19 pandemic.

The study examined the increasing incidence of RSV post-COVID-19 and a significant shift toward earlier RSV peaks in recent years (2021/2022, 2022/2023 and 2023/2024 seasons) in Ireland, with the onset and peak of the season nearly 2 months earlier than in pre-COVID-19 pandemic seasons (p

This analysis highlights an early seasonal onset and intensified RSV burden among infants in recent winters (2021/2022, 2022/2023 and 2023/2024 seasons). Quantifying the time lag for the community-level RSV transmission from infants and young children to older adults will offer insights to optimise RSV intervention strategies as a ‘life-course approach’ to alleviate healthcare system pressures during peak seasons.