In November 2023, Australia’s Therapeutic Goods Association approved ‘Nirsevimab’, a monoclonal antibody which provides passive immunity (lasting at least 5 months) to infants against respiratory syncytial virus (RSV).

Subsequently, in March 2024 the government of Western Australia announced a state funded program to provide Nirsevimab immunisation to newborns (at birth), those <8 months at start of the 2024 winter season (April – September), and at-risk infants <19 months.

RSV is highly contagious infection and a leading cause of hospitalisation in children aged under 5 years. Nirsevimab has shown to be >85% effective at preventing RSV associated hospitalisations in infants.

Many parents accepted the immunisation for their child, with over 22,000 doses of Nirsevimab being administered in WA. However, a cohort of parents chose to either decline Nirsevimab, or to delay it (which we define as initially declining the immunisation at first opportunity of availability, but later accepting it).

Here we outline findings from a qualitative study of ten parents in WA whose infants were eligible for Nirsevimab in 2024, and who opted to either delay or decline the immunisation. We explore factors and rationales for their choices; uncover how their Nirsevimab decision fit with their broader attitudes and perspectives towards vaccination, as well as their understanding of RSV infection; and discuss their reflections on their Nirsevimab decision. Key findings include parents' concerns around the ‘newness’ of Nirsevimab, anxiety as to potential immunisation safety risks (particularly in the post-COVID context), and perceptions that baby was not at high risk of being infected with RSV.

As RSV immunisation programs expand across Australia, and globally, this study contributes valuable knowledge around parental attitudes and decision-making pertaining to infant RSV immunisation. The findings should be considered by healthcare workers, policy makers, and immunisation program managers in their efforts to support RSV immunisation of infants.

Specific population groups are at an increased risk of severe infections from respiratory syncytial virus (RSV) including Aboriginal and/or Torres Strait Islander infants and children, those with medical conditions like chromosomal abnormalities, congenital heart and lung conditions and those born very preterm. Two strategies to reduce the RSV infant burden are now available: a single-dose monoclonal antibody for infants and a maternal vaccine; available in 2025 in a hybrid program. Understanding levels of disease awareness in high-risk groups and those from culturally and linguistically diverse (CALD) backgrounds is critical to develop appropriate communication strategies.

Through the holistic STAMP RSV program of work, we aimed to identify gaps in RSV awareness and perceived barriers to RSV immunisation to inform communication strategies across three population subgroups: Aboriginal and/or Torres Strait Islander, medically at-risk, and CALD (incorporating both immigrants and refugees).

We conducted a series of community pre-engagement activities to discuss the practicalities and desire for our proposed research. These activities identified a mix of one-on-one interviews and group discussions would be most appropriate. Building on interactions with community, we developed a program of proposed work consisting of in-depth interviews, focus groups and World Cafes with participants from the population subgroups across metropolitan and regional Western Australia. Working with community partners for recruitment, these interviews and group discussions will gather data on knowledge and awareness of RSV disease and immunisations, attitudes and willingness to accept RSV immunisation and types of educational resources wanted. Data collection is expected to be completed by May 2025.

Our findings will be used to develop and disseminate health education materials for RSV awareness and immunisation, specifically tailored to our three population subgroups. These findings will be vital for successful implementation of RSV immunisation programs, uptake of immunisations and increasing community literacy on a significant cause of infection in children.

Consultation for this project occurred through the Aboriginal Research Projects Forum, Our Children’s Health Research Aboriginal Advisors (OCHRAA), and community members in the Goldfields and Midwest regions. Ethical approval was obtained from the WA Aboriginal Health Ethics Committee and the Child & Adolescent Health Service Human Research Ethics Committee.

Background: The Northern Territory (NT) has some of the highest reported rates of both preterm birth and respiratory syncytial virus (RSV) infections globally. The aim of this study was to determine the influence of preterm birth on the risk of hospitalisation for RSV associated acute respiratory infection (RSV-ARI) among NT infants in their first year of life.
Materials and Methods: We assembled a retrospective NT population-based cohort of mother-infant pairs using perinatal and hospital inpatient datasets spanning a 10-year period from January 1st 2008 to December 31st 2017. Preterm birth was defined by a gestation of <37 weeks. RSV-ARI was defined by ICD-10-AM codes (J00-J22 or A37-A37.9 or H65-H67.8 or H72-H72.9). RSV-ARI risk was compared between preterm and term infants using a generalised linear regression model.
Results: The cohort comprised 31,513 babies born to 22,294 mothers. Overall, 9% were born preterm and these infants had approximately twice the risk of RSV-ALRI hospitalisation (4% versus 2%) compared to term born infants (RR 1.95, 95% CI 1.62-2.35). This finding remained significant after adjustment for demographics (e.g. remoteness, geography, age), obstetric complications, birth and infant characteristics (aRR 1.53, 95% CI 1.26-1.87). In the multivariate model, First Nations infants, infants of young mother (<19 years), those living remotely or in the central desert region also had a significantly higher risk of RSV-ALRI. In contrast, female infants, infants of women having their first pregnancy or receiving antenatal care in the first trimester had a significantly lower risk of RSV-ALRI.
Conclusion: Preterm birth is a substantial risk factor for infant RSV infections. Mothers at high-risk of preterm birth should consider earlier maternal RSV vaccination.

Context
In February 2025, NSW Health launched the RSV Prevention Program, introducing the Abrysvo vaccine for pregnant women through the National Immunisation Program (NIP) to protect newborns. In March 2025, the program’s second phase will introduce nirsevimab, a monoclonal antibody for eligible infants, expanding on the 2024 RSV Vulnerable Babies Program, where 85% of eligible infants received nirsevimab. Effective communication and stakeholder engagement are critical to overcoming barriers to implementation and public acceptance of new vaccines in a post-pandemic context.
Process
Lessons from the 2024 RSV Vulnerable Babies Program informed strategies to support the rollout and communication plan for the 2025 RSV Prevention program. Early engagement with stakeholders such as clinicians, specialists and midwives helped identify key resources for health professionals. Engagement with the NSW Health Maternity Consumer Reference Group during the development phase provided invaluable insights into what resources pregnant women valued to inform their decision making. Multiple rounds of comprehensive stakeholder engagement provided valuable insights but required managing conflicting perspectives to achieve effective messaging. This ensured messages were clear, accurate, and accessible while addressing safety, effectiveness, and potential side effects.
Analysis
Development and early implementation of RSV communications material highlighted key challenges in balancing scientific accuracy with accessibility. Communication strategies must avoid both excessive complexity and oversimplification, ensuring consumers receive enough information to make informed decisions. Additional challenges included explaining immunological concepts to the general population, such as passive vs. active immunisation and providing this information alongside other vaccination information for pregnant women.
Outcomes
Early and consistent communication is essential to securing health professional support and public trust. Separate materials were developed for clinicians and the general population to ensure information was relevant for them. Stakeholder and consumer feedback helped actively shape communications material and provided invaluable insights to how we communicate vaccination information to providers and the community beyond RSV vaccine.

Background: Respiratory syncytial virus (RSV) infection and associated hospitalisations represent a significant public health burden. In Australia, the hospitalisation rate for RSV from 2009 to 2017 was estimated at 54.8 per 100,000 population, with higher rates observed in high-risk groups such as children under 5 years and adults over 75 years.
In 2024, the Western Australia Government funded an RSV infant immunisation program, offering nirsevimab (Beyfortus) immunisation during the temperate winter season. However, the Kimberley and Pilbara regions in northern tropical Western Australia (WA) have historically shown variation in this winter seasonality.

Methods: An ecological study with time-series analysis is being conducted to document RSV seasonality in WA from January 1, 2012, to December 31, 2024. The study utilises RSV-associated hospitalisation records (Emergency Department Data Collection, Hospital Morbidity Data Collection) and RSV notification data (WA Notifiable Infectious Diseases Database), to document, analyse, and compare RSV seasonality in northern WA to the rest of WA.
This ongoing study will also utilise nirsevimab immunisation records (Australian Immunisation Register) to assess the impact of nirsevimab on RSV seasonality during 2024.

Results: Preliminary analysis indicates that RSV seasonality varies between northern WA and the rest of WA, with northern WA not following the winter seasonality seen in the rest of WA.
In northern WA, variation is seen from the rest of WA and between northern regions. In the generally tropical Kimberley region, ongoing transmission of RSV is observed without any clear seasonality. In the Pilbara region, transmission of RSV outside the winter season is evident, with the region experiencing prolonged seasonality.

Conclusions: Seasonal variation for RSV transmission outside the typical winter season is observed in the tropical regions of WA. Continued provision of RSV immunisation programs should be considered year-round in the northern regions of WA.

Background: Non-specific benefits of maternal seasonal influenza vaccine on all-cause acute lower respiratory infection (ALRI) hospitalisations have previously been reported. We examined non-specific effects of maternal seasonal influenza vaccine on respiratory syncytial virus (RSV) hospitalisations in Western Australian infants.
Methods: We conducted a population-based cohort study of births during 2010-2020 using individual-level, linked, longitudinal data on births, deaths, hospitalisations, antenatal immunisation records and routine respiratory viral testing. We performed Cox proportional hazard models with inverse probability treatment weighting, with maternal receipt of seasonal influenza vaccine during pregnancy as the exposure against the first RSV-confirmed hospitalisation in infants aged <6 months, adjusting for sociodemographic and perinatal factors.
Results: The cohort comprised 289,699 mother-infant pairs. Overall, 88,917 women (30.4%) received a maternal influenza vaccine. During the 10-year study period, there were 2,764 RSV-confirmed hospitalisations in infants aged <6 months, the majority (73.2%) occurring in infants whose mothers were unvaccinated. In unadjusted analyses, infants of vaccinated mothers had a higher RSV hospitalisation rate (20.3 per 1000 child-years [95% confidence interval, CI:91.4-21.2]) than those of unvaccinated mothers (16.8 per 1000 child-years [95%CI:15.6-18.0]). In adjusted analyses, receipt of maternal influenza vaccine was associated with a 14% reduction in RSV-hospitalisations (adjusted hazard ratio: 0.86 [95%CI:0.79-0.94]) compared with infants of unvaccinated mothers. After controlling for maternal health seeking behaviours, the point estimate suggested a reduction, but did not reach statistical significance (aHR: 0.98 [95%CI:0.87-1.10]). Analysis by trimesters and on pneumonia, bronchiolitis and all-cause ALRI-hospitalisations are ongoing.
Conclusion: Our findings suggest that maternal influenza vaccine may provide a beneficial non-specific effect against RSV-hospitalisations in infants and additional value of vaccines. Understanding the full public health value of a vaccine is important for policymakers and community to achieve maximum confidence in immunisation. These findings are particularly important with the ongoing implementation and future evaluation of RSV maternal vaccines.

Background:
RSV causes significant disease burden, but most Australian research focuses on hospital data only. This study provides a comprehensive analysis of RSV testing from both private and public pathology providers across multiple states, examining testing patterns and patient characteristics across care settings.

Methods:
We obtained de-identified RSV testing data from 1 September 2017 to 31 August 2023 from the three largest private pathology providers and two public providers in Australia. A descriptive analysis reporting RSV testing patterns in hospitals and the community, focusing on patient characteristics (age, sex, location, remoteness, and socioeconomic status) was performed. Continuous and categorical variables were compared using the Wilcoxon rank-sum and chi-square test, respectively.

Results:
Of 8,982,585 RSV tests conducted in New South Wales, Queensland and Victoria during the study period, 7.1% returned positive results. 5,744,059 (67.2%) were done in the community, compared to 3,238,526 (32.8%) in hospitalised patients (p<0.001). A higher percentage of females were tested (54.5%). Across all care settings analysed, test rates were highest in major cities. Children under 5 years had the highest testing rate at 18,432.5 per 100,000 population (from total annual population, 2017-2023) (p<0.001). Among individuals ≥15 years, those ≥75 years had the highest testing rate at 11,914 per 100,000. Higher socioeconomic groups (Q5) were more likely to be tested in the community and private settings, while middle socioeconomic groups (Q3) were most likely to be tested in public hospitals. Community test rates decreased stepwise with increasing socioeconomic disadvantage (p<0.001). Positive RSV test rates were highest in major cities (879.5 per 100,000), mainly in the community, and among higher socioeconomic groups (p<0.001).

Conclusion:
Our findings highlight the role of community testing, with high test volume and positivity rates and underscore the need for equitable testing across all socioeconomic and geographic areas to assess RSV burden and prioritise prevention.