Cost-Effectiveness of Vaccination Strategies to Control Future Mpox Outbreaks in England

OBJECTIVES: To determine the most cost-effective vaccination strategy for reducing future outbreaks of mpox among gay, bisexual, and other men who have sex with men (GBMSM) in the UK, following the 2022 outbreak.

METHODS: A validated deterministic compartmental model of mpox transmission and vaccination was used to project costs and outcomes in terms of incremental cost per quality-adjusted life year (ICER) over a 10-year period, discounted at 3.5% and a £30,000/QALY willingness-to-pay threshold. The model was parameterized using data from the 2022 outbreak and a GBMSM survey undertaken in December 2021 (RiiSH-MPOX). Different vaccination strategies were compared to no vaccination. Vaccine protection was assumed to last 1 or 3 years and have effectiveness of 78% and 89% for 1 and 2 doses. Cost inputs for vaccination, outbreak response, and case management were obtained from UKHSA, NHS standard costs or mpox-specific tariffs. Societal costs (absenteeism and presenteeism) for people with mpox were estimated using RiiSH-MPOX. QALYs were adapted from the Global Burden of Disease study.

RESULTS: The average total cost per mpox case was £2,772, driven by productivity losses (£1,601), followed by case-management (£755) and public health costs (£416). All vaccination strategies were cost-saving compared to no vaccination, irrespective of whether vaccination was only done during outbreaks (reactive) or pre-emptively irrespective of outbreaks. For a short duration vaccine (1-year protection), reactive vaccination was the most cost-saving strategy, resulting in savings of £75.07 million and 17.59 QALYs. However, if the vaccine provided 3-years protection, then pre-emptive vaccination was more cost-saving, saving £9.42 million and 11.18 QALYs. Sensitivity analyses supported vaccination if the vaccine cost was <£500.

CONCLUSIONS: Vaccinating against mpox is superior to no vaccination. Reactive vaccination is preferred if duration of protection is short; pre-emptive if longer duration. Analyses without productivity losses will be done as this is required to inform UK vaccine policy.