欧洲疾控中心-快速风险评估_欧盟_欧洲经济区多国爆发甲型肝炎（英）-2025.6_9页_804kb

Summary of the Multi-country Outbreak of Hepatitis A in the EU/EEA

Core Content

This document outlines a multi-country outbreak of hepatitis A in the European Union/European Economic Area (EU/EEA), primarily affecting adults experiencing homelessness, individuals who use or inject drugs, and those in poor sanitary conditions. The outbreak is associated with HAV subgenotype IB, with two distinct clusters identified in the region. The outbreak has been reported in Austria, Czechia, Hungary, and Slovakia, with Germany reporting a few isolated cases not linked to the outbreak.

The risk assessment highlights that the probability of infection is high among vulnerable groups, while the impact of the disease increases with age and is particularly severe for individuals with pre-existing liver conditions or those over 40 years old. The overall risk for these groups is moderate for those under 40 and high for adults 40 or older, whereas the risk for the general population is low to moderate.

Main Points

Epidemiological Situation

• Outbreak Period: January to May 2025.
• Affected Countries: Austria, Czechia, Hungary, Slovakia.
• High-risk Groups: Adults experiencing homelessness, people who use or inject drugs, and members of the Roma communities.
• Case Trends:
  • Austria: 87 confirmed cases, 44 under investigation, with a notable increase compared to 2024.
  • Czechia: 600 confirmed cases, with 18% from the Roma population.
  • Hungary: 641 suspected cases, 530 confirmed.
  • Slovakia: 880 cases in 2025, with a shift in affected demographics.
  • Germany: 3 non-fatal cases with no epidemiological link.

Microbiological Investigation

• Cluster a: Strain 3256048_HUN_2025 (Hungary), with 12 cases in Austria, 57 in Hungary, and 3 in Germany.
• Cluster b: Strain ERS23282329 (Slovakia), with cases in Austria and Slovakia.
• Genetic Variability: The two strains differ by a single nucleotide in the VP1/P2A junction, a highly variable region of the HAV genome.

Key Recommendations

Surveillance and Case Detection

• Enhance monitoring of HAV transmission routes to identify foodborne transmission and spill-overs into other high-risk groups.
• Sequence a representative subset of cases, ensuring diversity in region and population groups.
• Use the HAVnet protocol for sequencing, specifically the 460 bp region of the VP1/P2A junction.
• Share epidemiological and microbiological data with ECDC and other EU/EEA countries through EpiPulse Events.
• EU Health Task Force is available for support in outbreak response.

Vaccination Strategies

• Targeted pre-exposure vaccination for high-risk groups, including the Roma population, people experiencing homelessness, and people who inject drugs.
• Single-dose vaccination is effective in controlling outbreaks, but two doses are recommended for long-term protection, especially in adults 40 years or older.
• Post-exposure prophylaxis should be administered to close contacts of confirmed cases using the hepatitis A vaccine or immunoglobulins, as per national guidelines.
• Consider targeted vaccination in low and very low endemicity settings to provide individual health benefits.

Outreach and Communication

• Tailor outreach efforts to understand the needs, attitudes, and knowledge of high-risk populations.
• Adapt information to different languages and literacy levels, and address rumours and misinformation.
• Embed vaccination and hygiene interventions into existing services (e.g., shelters, food banks, drug treatment facilities).
• Ensure access to hygiene resources (e.g., water and soap) in areas where high-risk groups congregate.

Risk Assessment Overview

Limitations

• Under-ascertainment of HAV infections due to asymptomatic or mild cases.
• Limited sequencing data in many EU/EEA countries, which may affect the accuracy of identifying outbreak strains.
• Other outbreaks and clusters are being investigated but not included in this assessment due to different strains.

Conclusion

The multi-country outbreak of hepatitis A in the EU/EEA is primarily driven by poor sanitary conditions and risky behaviours, with a high probability of sustained transmission in vulnerable groups. Targeted vaccination and improved surveillance are critical in mitigating the spread and impact of the disease. The ECDC recommends strengthening outbreak response, enhancing sequencing efforts, and tailoring outreach to ensure effective prevention and control.