The Risk of Mpox (Monkeypox) Importation and Subsequent Outbreak Potential in Mainland China: A Retrospective Statistical Modelling Study

The 2022 mpox outbreak has spread rapidly across multiple countries in the non-endemic region, mainly among men who have sex with men (MSM), while China only has limited recorded importation and no local outbreak. We constructed probabilistic models to simulate the risk of mpox importation in mainland China, with the help of reported monkeypox cases during this multi-country outbreak and the international air-travel data. And we further evaluated the mpox outbreak potential given that undetected mpox infections were introduced into men who have sex with men, considering different transmissibility, population immunity and population activity. We found that the reduced international air-travel volume and stringent border entry policy decreased about 94% and 69% mpox importations respectively. Once a mpox case is introduced into active MSM population with almost no population immunity, the risk of triggering local transmission is estimated at 42%, and would rise to >95% with over six cases. Our study demonstrates the key role of the reduced international air-travel volume and stringent border entry policy during the COVID-19 pandemic on reducing mpox importations, and the subsequent risk of triggering local outbreaks among MSM.