Modelling the effectiveness of isolation strategies for managing mpox outbreaks with variable infectiousness profiles

The global outbreak of mpox (formerly monkeypox) in 2022 raised public awareness about the disease. The ensuing sporadic outbreaks in 2023 highlighted the importance of sustaining nonpharmaceutical interventions, such as case isolation and contact tracing. Using viral load data, we developed a modelling framework to characterize the various infectiousness profiles of infected individuals. We used this model to examine the potential effectiveness of two different possible isolation rules: specifically, rules permitting infected individuals to stop isolating after either a fixed-duration or following negative tests for infection. Our analysis showed large individual variations in the duration of viral shedding, ranging from about 23 to 50 days. The risk of infected individuals ending isolation too early (i.e., while they remained an infection risk) was estimated to be about 5% after 3 weeks of isolation. Unnecessary isolation after the end of the infectious period could be reduced by use of a testing-based rule. These findings support the choice of a 3-week isolation period following symptom onset if a fixed-duration rule is used, but also demonstrate how testing can mitigate unnecessarily prolonged isolation for those who have shorter infectious periods. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported in part by a National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (2022R1C1C2003637) (to K.S.K.); Scientific Research (KAKENHI) B 23H03497 (to S.I.); Grant-in-Aid for Transformative Research Areas 22H05215 (to S.I.); Grant-in-Aid for Challenging Research (Exploratory) 22K19829 (to S.I.); AMED CREST 19gm1310002 (to S.I.); AMED Research Program on Emerging and Re-emerging Infectious Diseases 22fk0108509 (to S.I.), 23fk0108684 (to S.I.), 23fk0108685 (to S.I.); AMED Research Program on HIV/AIDS 22fk0410052 (to S.I.); AMED Program for Basic and Clinical Research on Hepatitis 22fk0210094 (to S.I.); AMED Program on the Innovative Development and the Application of New Drugs for Hepatitis B 22fk0310504h0501 (to S.I.); AMED Strategic Research Program for Brain Sciences 22wm0425011s0302; AMED JP22dm0307009 (to K.A.); JST MIRAI JPMJMI22G1 (to S.I.); Moonshot R&D JPMJMS2021 (to K.A. and S.I.) and JPMJMS2025 (to S.I.); Institute of AI and Beyond at the University of Tokyo (to K.A.); Shin-Nihon of Advanced Medical Research (to S.I.); SECOM Science and Technology Foundation (to S.I.); The Japan Prize Foundation (to S.I.). The collaboration between R.N.T. and S.I. was supported by a Royal Society International Exchange award (grant number IES-R3-193037). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study involves only openly available human data, which can be obtained from the original articles summarized in Supplementary Table 1. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.