Cost-effectiveness of vaccination strategies to control future mpox outbreaks in England: a modelling study

In 2022, a global mpox outbreak occurred among gay and bisexual men who have sex with men (GBMSM). In England, the outbreak was controlled through reductions in sexual risk behaviour and vaccination of high-risk GBMSM. However, mpox continues to circulate, including an expanding outbreak in Africa. We evaluated the most cost-effective vaccination strategy to minimise future mpox outbreaks among GBMSM in England.

A mathematical model of mpox transmission among GBMSM was developed to estimate the costs per quality-adjusted-life-year (QALY) gained for different vaccination strategies starting in 2024 (10-year time-horizon; 3.5% discount rate; willingness-to-pay threshold £20,000/QALY). Reactive vaccination (only during outbreaks) and/or pre-emptive vaccination (continuous routine) strategies targeting high-risk GBMSM were compared to no vaccination. Baseline projections assumed importation of new mpox cases, and a vaccine effectiveness following 1/2 doses of 78%/89% for 5/10 years at £160/dose. Costs were estimated for case management, vaccination and public health responses during an outbreak.

All vaccination strategies reduced future outbreaks, gained QALYs and reduced costs compared to no vaccination. Continuous pre-emptive vaccination (daily rate 54 doses) with reactive vaccination (daily rate 81 doses) if there is an outbreak was most cost-effective, saving £8.8 million and gaining 108.6 QALYs over 10-years. Vaccination remains cost-effective if the vaccine costs less than £330/dose. Pre-emptive with reactive vaccination remains the preferred strategy across many sensitivity analyses, with just pre-emptive vaccination at a higher rate becoming the preferred strategy in some sensitivity analyses. Just reactive vaccination only becomes the preferred strategy when public health response costs are not included, and in this case the vaccine has to cost less than £110 per dose for vaccination to be cost-effective.

Vaccination of high-risk GBMSM is likely to be a cost-saving strategy for preventing future mpox outbreaks.

NIHR and Wellcome Trust.