Modelling the potential spread of Clade Ib MPXV in Asian cities
Shihui Jin1, Gregory Gan1, Akira Endo1,2,3
1Saw Swee Hock School of Public Health, National University of Singapore, Singapore.
Background:
The ongoing 2023-2024 mpox outbreak in several African countries, driven by the novel Clade Ib strain, has resulted in imported cases being reported in Sweden, Thailand and India. The potential 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 policymaking and resource planning.
Methods:
A compartmental model was constructed to characterise 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 counts in 1 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% (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 1 year.
Interpretation:
A potential mpox outbreak in an Asian setting could be alleviated through strong surveillance and a timely response from stakeholders. NPIs are recommended for outbreak management due to their demonstrated effectiveness and practicability.
Insights
The novel mpox Clade Ib strain poses a risk to Asia. Non-pharmaceutical interventions like isolation and quarantine are effective in controlling potential mpox outbreaks.
Area of Science:
- Epidemiology
- Mathematical Modeling
- Public Health
Background:
- The 2023-2024 mpox outbreak involves a novel Clade Ib strain with high transmissibility.
- Imported cases have been reported in Asia, raising concerns about potential community-wide transmission.
- Limited knowledge of mpox transmission dynamics hinders effective policymaking and resource planning.
Purpose of the Study:
- To characterize potential mpox transmission dynamics in Asian cities.
- To simulate importation-triggered outbreaks and assess the impact of non-pharmaceutical interventions (NPIs).
Main Methods:
- A compartmental model was developed to simulate mpox transmission.
- Outbreaks were simulated in 37 Asian cities under various initial infection scenarios.
- The effectiveness of isolation and quarantine measures was projected.
Main Results:
- Outbreak sizes varied significantly among Asian cities, with higher risks in populations with high sexual activity or low smallpox vaccination immunity.
- Simulations projected up to 340 cases per million residents in one scenario without interventions.
- Isolation reduced outbreak size by up to 88%, and quarantining contacts further decreased cases by 22 percentage points.
Conclusions:
- Strong surveillance and timely responses are crucial for managing potential mpox outbreaks in Asia.
- Non-pharmaceutical interventions (NPIs) are practical and effective for mpox outbreak management.
Related Concept Videos
01:09Mutation, Gene Flow, and Genetic Drift
00:36Viral Mutations