Modelling the potential spread of Clade Ib MPXV in an Asia Pacific city

Abstract

Background The ongoing 2024 mpox outbreak in several African countries, driven by the novel Clade 1b strain, has resulted in imported cases being reported in Sweden and Thailand. The Asia Pacific (APAC) region, with little exposure to previous mpox waves, is particularly vulnerable to local transmission triggered by importation. While this highlights the importance of early preparedness, current knowledge of the virus's transmission dynamics remains too limited to effectively inform policy-making and resource planning. Methods A compartmental model was constructed to characterise the potential mpox transmission triggered by importation in an APAC city. Outbreaks were simulated under diverse hypothetical scenarios considering transmission mechanisms, different affected subpopulations, levels of disease transmissibility, and importation frequencies. The impacts of various non-pharmaceutical interventions (NPIs) including isolation, and vaccination strategies were projected and compared. Findings Up to 30% of the population would be infected in the scenario of high sexual and moderate non-sexual transmissibility in the general community, with minimal impact from importation frequency on outbreak size and healthcare burden. The sequential introduction of mandatory home isolation for diagnosed cases, pre-departure screening of international arrivals, and contact tracing were projected to lower the peak outbreak size by 35%, 0.04%, and 1.1%, respectively, while the reduction would be 30% with proper vaccination by prioritising the sexually active group. These measures would significantly decrease disease morbidity and mortality rates, thereby alleviating the disease's pressure on healthcare systems. Interpretation The potential mpox outbreak in the APAC setting could be alleviated through strong surveillance and timely response from stakeholders. NPIs are recommended over vaccination for outbreak management due to their demonstrated effectiveness and practicability.