Authors' objectives: Infections by the Respiratory Syncytial Virus (RSV) can cause serious lower respiratory tract (lung) disease and are a major source of disease burden in young children during their first years of life. Infants are particularly at risk of severe RSV infection. Two new products recently arrived on the Belgian market to prevent RSV disease by passive immunisation: a maternal vaccine (Abrysvo®) given between 32 and 36 weeks of pregnancy to prevent RSV in babies from birth through 6 months of age; and a monoclonal antibody (nirsevimab, Beyfortus®) to be injected in infants of unvaccinated mothers once before the RSV season starts, or at birth for infants born during the RSV season. This KCE study will assess the risk-benefit balance of these two products, as well as the expected cost-effectiveness of Belgian programmes using them. The results are expected by June 2025.

Authors' results and conclusions: Although an increasing number of RSV cost-effectiveness analyses have been published in Europe, most have focused on comparing a single intervention to standard care, with several estimating cost-effective price thresholds based on specific official or arbitrary WTP thresholds. Conducting economic evaluation by constructing a decision environment in which not all available and feasible options are compared head-to-head, will lead to fundamentally misleading results for policy. Therefore, we conducted a full incremental analysis comparing all relevant strategies within the Belgian context in consultation with a diverse advisory panel of Belgian clinical and public health experts. As shown in Table 52 and Table 54, the ICERs for the seasonal plus catch-up mAb strategy were substantially lower (i.e. more attractive) when compared simply to no intervention rather than to the appropriate next best alternative strategy. Our analysis can be compared with three previously published full incremental cost-effectiveness analyses: Li et al. (2022) 81 in Norway, Getaneh et al. (2023) 83 in six European countries (England, Scotland, Finland, Denmark, Netherlands, Veneto region of Italy) and Hodgson et al. (2024) 165 in England. Our analysis found for comparable intervention options higher threshold intervention costs per dose at which these interventions can be considered cost-effective than Li et al.81, 83 found for any of the 7 countries using a similar static model structure, two to three years ago. The primary reason is that Belgium has substantially higher RSV-coded hospitalisation rates compared to these six countries. Moreover, in our baseline analysis, in addition to assuming that these interventions prevent RSV attributable infant mortality, we were able to use more recent and more favourable information on efficacy and duration of protection (e.g., 6 months duration of protection for both mAb and MV). Hodgson et al.165 used a dynamic transmission model, comparing four strategies both to ‘no intervention’ and to one another. They also performed a similar two-way threshold analysis using the UK’s official WTP threshold of £20,000 per QALY gained. They concluded that a seasonal mAb programme could be cost-effective up to £84, while seasonal MV could be cost-effective up to £80 at all-inclusive cost. The main driver of the difference with our findings for Belgium was again the higher hospitalisation incidence rate used in our analysis. Moreover, the National Health Service costs per GP visit (£35), non-ICU admission (£1,100), and ICU admission (£2,905) were substantially lower than the corresponding costs in Belgium. Furthermore, Hodgson et al. attributed lower QALY losses for both MA and non-MA episodes. Our study has several strengths. It incorporated age-specific national disease burden data, representative cost and quality of life data, and the pooled clinical evidence from systematic literature review, to inform the model, thus providing valuable information to support evidence-based decision- making. Moreover, we applied a wide range of WTP thresholds and conducted advanced probabilistic sensitivity analyses (including value of perfect information and net loss analyses), scenario analyses and two-way threshold analyses, enhancing the relevance of our findings for decision-makers and programme managers, particularly during price negotiations and public tender processes. Finally, we were able to incorporate the latest real-world effectiveness data. Our study also has several limitations. First, we employed a static model, which does not account for herd immunity. However, given (a) that no intervention would be targeted at infants over the age of 6 months, (b) the relatively short duration of protection for both MV and mAb, and (c) that the role of infants in RSV transmission is predominantly that of a “sink”, rather than a transmitter of the pathogen, the impact of this limitation on our results is likely limited. Furthermore, a model comparison analysis using both static and dynamic frameworks for these types of RSV interventions demonstrated similar outcomes when applying the same set of input parameters. 85 Second, since RSV-associated otitis media166 was not accounted for in our analysis due to lack of data, the overall health and economic benefits of RSV prevention strategies may be underestimated. Third, our analysis did not account for MV protection of the pregnant women themselves, as this efficacy was not assessed in RCTs. This may result in a slight underestimation of MV impact. This underestimation is likely limited, given that RSV episodes in healthy adults under 60 years are generally mild, and pregnant mothers constitute a small subgroup in the total adult population at any one time, and are not core transmitters of the pathogen. Finally, although our study used the disease burden observed in the presence of a palivizumab programme for high risk children in Belgium as the ‘no intervention’ comparator, we did not account for potential cost offsets from replacing palivizumab with nirsevimab in high-risk children, because this decision was considered to be taken, and therefore separate from the expansion of the programme to all infants. It is useful to note that in a full cost-effectiveness framework where all strategies are compared to each other, not just to ‘no intervention’, this omission is unlikely to affect the preferred strategy, as ‘no intervention’ is already a strongly dominated option.

Project Status: Completed

URL for project: https://kce.fgov.be/en/lopende-en-geplande-studies/ongoing-projects/study-2024-51-hta-cost-effectiveness-of-maternal-immunisation-by-abrysvor-or-a-single-injection-of-a

Year Published: 2025

URL for published report: https://doi.org/10.57598/R402C

URL for additional information: https://kce.fgov.be/en/publications/all-reports/cost-effectiveness-of-new-preventive-options-against-rsv-infections-in-belgian-infants

English language abstract: An English language summary is available

Publication Type: Rapid Review

Country: Belgium

DOI: 10.57598/R402C

Organisation Name: Belgian Health Care Knowledge Centre

Contact Address: Administrative Centre Botanique, Doorbuilding (10th floor), Boulevard du Jardin Botanique 55, B-1000 Brussels, Belgium tel: +32 2 287 33 88 fax: +32 2 287 33 85

Contact Name: info@kce.fgov.be

Contact Email: info@kce.fgov.be

Copyright: <p>Belgian Health Care Knowledge Centre (KCE)</p>