欧洲疾控中心-威胁评估简报_在欧盟_欧洲经济区检测猴痘病毒Ib支的本地传播（英）-2025.10_11页_636kb

Summary of Threat Assessment Brief: Detection of Autochthonous Transmission of Monkeypox Virus Clade Ib in the EU/EEA

Core Content

This Threat Assessment Brief evaluates the risk of autochthonous (local) transmission of Monkeypox Virus (MPXV) clade Ib in the EU/EEA, with a focus on male-to-male sexual transmission. It outlines the current epidemiological situation, risk assessment, and recommendations for public health authorities.

Main Points

• Epidemiological Situation:

  • Spain reported its first locally acquired clade Ib mpox case on 10 October 2025.
  • Four additional clade Ib mpox cases were reported in Italy, Portugal, and the Netherlands on 17 October 2025, all among males without travel history.
  • These cases indicate that transmission may be occurring within sexual networks among men who have sex with men (MSM) in several EU/EEA countries.
  • Previous clade I mpox cases in the EU/EEA were all imported or linked to imported cases, with limited onward transmission mainly to household contacts.
  • In the United States, limited transmission of clade I mpox has been reported among MSM, with some hospitalisations.

• Risk Assessment:

  • The overall risk of MPXV clade Ib infection is moderate for MSM and low for the general population.
  • Past infection with MPXV clade II or immunisation with smallpox/mpox vaccine (especially two doses) may reduce the risk of infection and disease severity.
  • The vaccine effectiveness for two pre-exposure doses is estimated at 82% (95% CI: 72–92), while one dose provides 76% (95% CI: 64–88) effectiveness.
  • Post-exposure vaccination effectiveness is estimated at 20% (95% CI: -24–65).
  • The case fatality ratio (CFR) for clade Ib in Africa is less than 1%, and is expected to be even lower in the EU/EEA due to better healthcare and lower HIV prevalence.

• Recommendations:

  • Surveillance and Testing: Ensure laboratory testing is accessible, especially in locations serving MSM. Maintain event-based and indicator-based surveillance.
  • Case Reporting: Report all clade I cases promptly to EpiPulse and provide detailed information on vaccination status, clade, travel history, HIV status, and outcomes.
  • Vaccination: Offer vaccination to individuals at higher risk, including MSM and those with HIV. Public health authorities should communicate the need for vaccination.
  • Contact Tracing: Implement effective contact tracing to prevent onward transmission. Use specialised software and maintain data confidentiality.
  • Risk Communication: Engage with civil society organisations and community-based groups to improve awareness, trust, and vaccination coverage among MSM.

Key Information

• Autochthonous Transmission: First locally acquired clade Ib mpox case in Spain, with additional cases in Italy, Portugal, and the Netherlands, all without travel history.
• Transmission Dynamics: Transmission is likely occurring within sexual networks of MSM, indicating a shift from previous patterns.
• Vaccine Effectiveness: Two pre-exposure doses provide high effectiveness (82%) against MPXV clade Ib, while post-exposure vaccination effectiveness is lower (20%).
• Severity: Limited data on severity in the EU/EEA, but most cases have mild symptoms and good outcomes. HIV-positive individuals, especially those with untreated HIV, are at higher risk.
• Outbreak Probability: Mathematical models suggest that small outbreaks (10-100 cases) are probable in larger cities if clade Ib is introduced into MSM sexual networks. Larger outbreaks are less likely unless clade Ib is more transmissible than clade II.

Knowledge Gaps

• Transmissibility: Limited evidence on the transmissibility of clade Ib compared to clade II.
• Severity and Clinical Course: Need for more data on the severity and differences in clinical outcomes between clade Ib and clade II.
• Immunity Levels: Understanding of waning immunity from prior clade II infections or vaccination.
• Vaccine Efficacy: Further research is needed on the long-term efficacy and safety of booster doses, including different administration routes.
• Behavioral Patterns: Insights into sexual contact patterns of MSM in the EU/EEA to better guide interventions.

Conclusion

The risk of MPXV clade Ib infection in the EU/EEA is moderate for MSM and low for the general population. Public health authorities are advised to enhance surveillance, improve vaccination coverage, and engage with communities to mitigate the risk of further transmission. Continued monitoring and research are essential to address knowledge gaps and refine risk assessments.