RSV incidence in Queensland infants varies by climate and household factors, study finds

Respiratory syncytial virus (RSV) incidence in Queensland children aged under 2 years is higher in temperate and arid or semi-arid regions and larger families, an Australian retrospective cohort study finds.

Writing in BMC Public Health, the study authors noted that baseline epidemiological data were needed to evaluate the impact of the national RSV Mother and Infant Protection Program, which was introduced in February 2024, and to identify populations at higher risk.

Professor Ian Barr, Deputy Director of the WHO Collaborating Centre for Reference and Research on Influenza, Melbourne, explained that the RSV Mother and Infant Protection Program was designed to prevent RSV infections in newborns for the first six months, or possibly longer.

‘Mothers can be vaccinated against RSV during pregnancy, allowing antibodies to cross the placenta and protect the newborn, or infants can be given the long-acting monoclonal antibody nirsevimab shortly after birth.’

The authors analysed all RSV notifications in Queensland children aged under 2 years between 2022 and 2023 using the Queensland Notifiable Conditions System, examining incidence by age, epidemiological week, climate zone and community-level characteristics.

A total of 18,683 RSV notifications were recorded in this age group, corresponding to an overall incidence of 79.7 per 1000 children in 2022 and 84.8 per 1000 children in 2023. Incidence was highest among infants aged 1 month (96.6 per 1000) and 12 months (96.7 per 1000), and remained consistently high from 1 to 15 months of age.

Compared with tropical climates, RSV incidence was higher in warm temperate zones (adjusted risk ratio [aRR], 1.26) and arid or semi-arid zones (aRR, 1.18). Patterns of seasonal RSV epidemics differed across climate zones, with more distinct winter peaks in temperate regions and more year-round activity (or monsoonal peaks) in tropical areas.

RSV incidence was higher in areas with larger family sizes, with a 39% increase for each additional child per household by postcode (aRR, 1.39), whereas remoteness was associated with lower recorded incidence (aRR, 0.89).

Multiple high-incidence clusters were identified within major population centres, including Greater Brisbane, Townsville and surrounds, Darling Downs and the Gold Coast. Regional clusters were also noted in the Aboriginal Shire of Woorabinda, the Longreach area, Hervey Bay-Maryborough and Roma areas.

Professor Barr said that as the findings were based on laboratory notifications, ‘regions with low levels of testing or poor access to medical facilities may be underestimated in their RSV rates.’ He added, ‘Only two RSV seasons were analysed and these were immediately after the rebound in RSV following COVID-19, so the seasonality of RSV may change somewhat in future years.’

The authors concluded that future RSV prevention strategies should consider climatic variation and community-level factors, and highlighted a potential gap in protection for older infants beyond 6 months of age as immunity from maternal vaccination and birth dose therapeutics waned.

Professor Barr said the findings did not change the overall approach for GPs, but reinforced the importance of prevention.

‘This study makes a strong case for preventing RSV infection in newborns either by maternal vaccination or monoclonal antibody treatment of newborns, not only in Queensland but throughout Australia,’ he said.

BMC Public Health 2026; 26: 615.

This summary includes content created using editorial tools, including AI, and was reviewed by editors prior to publication.