Modelling the potential spread of Clade Ib MPXV in Asian cities
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background
The ongoing 2023–2024 mpox outbreak in several African countries, driven by the novel Clade Ib strain, has resulted in imported cases reported in Sweden, Thailand, and India. The potentially high transmissibility of this new strain and shifts in transmission modes may make territories in Asia, which were minimally affected by previous mpox waves, susceptible to community-wide transmission following 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 dynamics. Importation-triggered outbreaks were simulated in 37 Asian cities under scenarios with one, three, and five initial local infections. The impacts of various non-pharmaceutical interventions (NPIs), including isolation and quarantine, were projected and compared.
Findings
Our simulations revealed substantial disparities in outbreak sizes among the 37 Asian cities, with large-scale outbreaks expected in territories with a high proportion of sexually active individuals at risk or low immunity from smallpox vaccination. Total case count in one year following initial local infections would increase linearly with initial infection size. In the scenario with three initial local infections, up to 340 cases per million residents were expected without interventions. Isolation for diagnosed cases was projected to lower the outbreak size by 43.8% (interquartile range [IQR]: 42.7%–44.5%), 67.8% (IQR: 66.5%–68.9%), 80.8% (IQR: 79.5%–82.0%), and 88.0% (IQR: 86.8%–89.1%) when it reduced interpersonal contacts by 25%, 50%, 75%, and 100%, respectively. Quarantining close contacts would contribute to a further decrease in cases of up to 22 percentage points over one year.
Interpretation
The potential mpox outbreak in an Asian setting could be alleviated through strong surveillance and timely response from stakeholders. NPIs are recommended for outbreak management due to their demonstrated effectiveness and practicability.
KEY MESSAGES
What is already known on this topic
Clade Ib monkeypox virus (MPXV) is circulating in the Democratic Republic of the Congo (DRC) and its neighbouring countries, with imported cases being identified globally. Meanwhile, evidence indicates that the virus can be transmitted through both sexual and non-sexual routes, raising concerns about its potential spread in the general population. To prevent a global outbreak, the World Health Organization (WHO) suggested countries around the globe to prepare in advance.
What this study adds
Our simulations quantified the potential disease burden of an mpox outbreak triggered by a once-time importation event in 37 major Asian cities with varying pre-existing immunity levels and populations at higher risk due to frequent sexual activities. The compartmental modelling framework developed in this study also projected the effectiveness of diverse non-pharmaceutical intervention (NPI) strategies in outbreak control, providing policy-makers with guidance for effective public health crisis management.
How this study might affect research, practice or policy
An importation-triggered mpox outbreak can be substantially mitigated with powerful disease surveillance and a prompt response of the stakeholders, but may also lead to severe consequences with high morbidity and mortality if not addressed in time in cities with a large highly sexually active population. Various NPIs, particularly isolating infected cases, are recommended for curbing the disease outbreak due to their feasibility and effectiveness in the Asian setting.
