Respiratory syncytial virus (RSV) vaccination program for older Australians reduces health inequalities: a distributional cost-effectiveness analysis

INTRODUCTION: Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract disease in individuals aged ≥75 years. Differences in disease burden and vaccine uptake by socio-economic status (SES) are important considerations but are not usually incorporated into traditional cost-effectiveness analyses. We conducted a distributional cost-effectiveness analysis (DCEA) to evaluate RSV vaccination programs for older Australians. METHODS: We utilised a static multi-cohort Markov model to simulate age- and SES-specific RSV disease progression in adults aged ≥75 years, comparing no vaccination with the two currently approved RSV vaccines in Australia (Arexvy and Abrysvo). Where available, we used age and SES stratified healthcare utilisation data for RSV as input in the model, with SES represented by the Index of Relative Socio-economic Disadvantage (IRSD). Net health benefits were calculated considering the opportunity costs associated with the vaccination program. We transformed the health distribution from no vaccination and vaccination scenarios and then compared these using a social welfare function. RESULTS: We found that all IRSD subgroups benefited from vaccination. Disadvantaged subgroups received larger health benefits, despite relatively lower vaccination uptake, due to higher baseline probability of RSV-related hospitalisation and death. Under the base-case assumptions, including an assumed negotiated price of A$150 per vaccine dose and an opportunity cost threshold of A$50,000 per quality-adjusted life year for all IRSD subgroups, we found an increase in equity and an overall increase in net health benefit. The impact of vaccination on net health and on equity was sensitive to annual RSV incidence, probability of symptomatic RSV episode, vaccine efficacies against RSV hospitalisation, and vaccine price. CONCLUSION: RSV vaccination for Australians aged ≥75 years could improve overall population health and reduce existing health inequalities. However, the net health benefits were sensitive to the potential vaccine price to be negotiated by the government in Australia for older adults.