Eurosurveillance - Current Issue -Volume 31, Issue 14, 09/Apr/2026

Monkeypox virus (MPXV) has spread globally to non-endemic countries in recent years and has the potential to cause recurrent outbreaks. Vaccine breakthrough infections and reinfections are suggested to be linked to immunity waning over time.

We aimed to determine how long individuals remain protected following MPXV infection and if vaccination can be used as a public heath measure to elicit durable protective immune responses.

This retrospective observational study investigated the durability of humoral immune responses in a longitudinal cohort of 46 individuals infected with MPXV during the 2022 global mpox outbreak. We collected 86 blood samples up to 7 months after infection, and analysed the antibody responses against MPXV with a serological assay using a panel of eight viral antigens.

Monitoring of antibody kinetics revealed transient IgM responses in the first weeks following infection and a robust polyclonal IgG response that peaked 1–2 months after infection but declined consistently in the following months. Post-exposure immunisation with third-generation modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine did not seem to increase significantly the strength, breadth or longevity of antibody responses. Using a separate cohort of 25 uninfected long-term MVA-BN vaccinees, we observed low to undetectable seropositivity against most MPXV antigens after 30 months.

As circulating antibody titres have been identified as a correlate of protection against mpox, declining antibody levels raise concerns for mpox susceptibility in previously infected and vaccinated persons. This warrants further evaluation of long-term vaccine effectiveness to inform booster vaccination guidance.

Up-to-date estimates of chronic hepatitis B virus (HBV) prevalence in both general and key populations are challenging to obtain because of underdiagnosis, heterogeneous surveillance systems and underrepresentation of key populations.

We aimed to test the Workbook Method to estimate chronic HBV prevalence in 2022 across the EU/EEA, by country and among men who have sex with men (MSM), people who inject drugs (PWID) and migrants.

We used the Robert Koch Institute’s version of the Joint United Nations Programme on HIV/AIDS (UNAIDS) Workbook Method to generate HBV prevalence estimates for each EU/EEA country and for MSM, PWID and migrants within each country. We combined data on population size and HBV prevalence for each population group gathered from scientific sources and reviewed by the European Centre for Disease Prevention and Control’s hepatitis national contact points.

Overall, 0.7% (lower bound–upper bound: 0.5–0.9%) of the EU/EEA population (3,226,000 (2,397,000–4,149,000) individuals) were estimated to be living with HBV in 2022. National HBV prevalence ranged from 0.1% (0.1–1.0%) to 3.1% (2.8–3.3%). Prevalence estimates varied from 0.8% (0.5–1.0%) to 10.5% (9.3–11.9%) for migrants, < 0.1% to 8.7% (lower and upper bounds not available) for PWID and from < 0.1% (< 0.1– < 0.1%) to 10.5% (10.2–10.8%) for MSM.

Despite limitations, including the inability to address overlapping populations, these estimates confirm substantial chronic HBV prevalence in the EU/EEA, with considerable variation between countries and population groups. This relatively straightforward method offers an alternative means of generating HBV prevalence estimates.