Work

Informing an mpox stockpile investment case: epidemiological modelling and cost–benefit analysis

Year: 2026

Type: article

Abstract: BACKGROUND: In response to ongoing mpox outbreaks, Gavi, the Vaccine Alliance, was considering funding the establishment of an mpox vaccine stockpile. To support their decision making, Gavi commissioned the Center for Outbreak Response Innovation at the Johns Hopkins Bloomberg School of Public Health to estimate the optimal size, impact, health benefits, and monetised net benefits of different mpox vaccine stockpile sizes for an effective global stockpile to support outbreak containment and prevention of widespread mpox transmission. We aimed to quantify the potential impact of vaccination on future mpox outbreaks to inform Gavi's decision making for investing in an effective mpox vaccine stockpile. METHODS: A deterministic compartmental model of mpox transmission with vaccine interventions was developed, including intervening rapidly-at 20 cases reported-versus at 100 cases reported. The model was used to assess potential vaccine-based mitigation strategies for mpox outbreaks in Gavi-eligible countries by simulating mpox transmission and control dynamics, given two vaccination strategies (one dose and two doses) compared with no intervention in high-risk groups and contacts of cases, across four distinct subpopulations: (1) children younger than 5 years, (2) men who have sex with men, (3) female sex workers, and (4) the remaining general population. The findings from this model were incorporated into a Monte Carlo cost-benefit analysis of different stockpile sizes. FINDINGS: Rapid response (ie, intervening at 20 cases reported) using a single-dose vaccination strategy provided the greatest benefits relative to costs compared with a two-dose strategy. Using a one-dose strategy, expected net benefits were estimated to be over US$81 million to $220 million higher when responding to outbreaks rapidly than when responding after 100 cases. Furthermore, the total cost per disability-adjusted life-year (DALY) averted with rapid response using a one-dose vaccine strategy responding at 20 cases was 18% to 53% lower than a one-dose strategy introduced at 100 cases. A stockpile of 1 000 000 doses had the highest ratio of benefits to costs. INTERPRETATION: A stockpile calibrated to attain a high ratio of benefits to costs can be effective in controlling outbreaks and reducing overall negative health impacts. The cost-effectiveness of mpox vaccine stockpiles could be further maximised with reduced vaccine pricing and dose-sparing strategies. FUNDING: Gavi, the Vaccine Alliance.

Source: The Lancet Global Health

DOI: 10.1016/j.langlo.2026.104069