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Original research
Modelling the impact of vaccination and sexual behaviour adaptations on mpox cases in the USA during the 2022 outbreak
  1. Patrick A Clay1,
  2. Jason M Asher2,
  3. Neal Carnes3,
  4. Casey E Copen1,
  5. Kevin P Delaney3,
  6. Daniel C Payne4,
  7. Emily D Pollock1,
  8. Jonathan Mermin5,
  9. Yoshinori Nakazawa3,
  10. William Still6,
  11. Anil T Mangla6,
  12. Ian H Spicknall1
  1. 1 Division of STD Prevention, National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  2. 2 Office of the Director, Center for Forecasting and Outbreak Analytics, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  3. 3 Division of HIV Prevention, National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  4. 4 Division of Foodborne, Waterborne & Environmental Diseases, National Center for Emerging & Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  5. 5 Office of the Director, National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  6. 6 DC Department of Health, Washington, District of Columbia, USA
  1. Correspondence to Dr Patrick A Clay, Division of STD Prevention, CDC, Atlanta, Georgia, USA; ruq9{at}cdc.gov

Abstract

Background The 2022 mpox outbreak has infected over 30 000 people in the USA, with cases declining since mid-August. Infections were commonly associated with sexual contact between men. Interventions to mitigate the outbreak included vaccination and a reduction in sexual partnerships. Understanding the contributions of these interventions to decreasing cases can inform future public health efforts.

Methods We fit a dynamic network transmission model to mpox cases reported by Washington DC through 10 January 2023. This model incorporated both vaccine administration data and reported reductions in sexual partner acquisition by gay, bisexual or other men who have sex with men (MSM). The model output consisted of daily cases over time with or without vaccination and/or behavioural adaptation.

Results We found that initial declines in cases were likely caused by behavioural adaptations. One year into the outbreak, vaccination and behavioural adaptation together prevented an estimated 84% (IQR 67% to 91%) of cases. Vaccination alone averted 79% (IQR 64% to 88%) of cases and behavioural adaptation alone averted 25% (IQR 10% to 42%) of cases. We further found that in the absence of vaccination, behavioural adaptation would have reduced the number of cases, but would have prolonged the outbreak.

Conclusions We found that initial declines in cases were likely caused by behavioural adaptation, but vaccination averted more cases overall and was key to hastening outbreak conclusion. Overall, this indicates that outreach to encourage individuals to protect themselves from infection was vital in the early stages of the mpox outbreak, but that combination with a robust vaccination programme hastened outbreak conclusion.

  • VACCINATION
  • Sexual Behavior
  • Models, Theoretical

Data availability statement

Data are available upon reasonable request. Data and code are available upon reasonable request.

https://doi.org/10.1136/sextrans-2023-055922

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    Data availability statement

    Data are available upon reasonable request. Data and code are available upon reasonable request.

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    Footnotes

    • Handling editor Michael Traeger

    • Contributors The manuscript concept was designed by PAC, IHS, JM, YN. The model was designed by PAC, IHS and EDP. JMA advised on model structure. NC, CEC and KPD provided inputs on modelling of behaviour. DCP provided inputs on modelling of vaccination. WS and ATM provided epidemiological data from DC. The manuscript was primarily written by PAC, with inputs from all authors. PAC assumes responsibilities as the guarantor of this study, and accepts full responsibility for the finished work.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.