Eurosurveillance - Volume 30, Issue 44, 06 November 2025

Older adults are at increased risk of severe chikungunya. Some countries advise against vaccinating ≥ 60 or ≥ 65-year-olds with the licenced live-attenuated vaccine (CHIKV LA, IXCHIQ), following severe adverse event (SAE) reports. A virus-like particle vaccine (CHIKV VLP, VIMKUNYA) is licensed in the United States (US), EU/EEA and the United Kingdom. Up to 31 August 2025, over 12,500 doses were administered in US and Germany; no SAEs in ≥ 65-year-olds were reported. Early post-authorisation data support its favourable safety profile in ≥ 65-year-olds.

In Spain during March–April 2024, an outbreak of invasive meningococcal disease (IMD) occurred in four young adults, exhibiting high case fatality with two deaths. Cases 1 and 4 were confirmed by isolation of Neisseria meningitidis from blood samples, while Cases 2 and 3 were PCR-confirmed from cerebrospinal fluid (CSF). Serogroup B meningococcus with identical characterisation (B: 19–54, 15: F5–1: ST-34, cc32) was identified for all cases; the outbreak strain genosubtype PorA_VR1: 19–54 had not been previously described. Potential coverage of the outbreak strain by available MenB vaccines could not be predicted by molecular tools, so bactericidal response to the 4CMenB vaccine against the outbreak strain was measured by human serum bactericidal antibody assay (hSBA), defining the strain as covered by the vaccine. Two different social events were involved in transmission of the outbreak strain. According to the national meningococcal disease surveillance protocol, an active search for close contacts of the cases was conducted by public health authorities and timely chemoprophylaxis and/or vaccination with 4CMenB vaccine was recommended to over 200 contacts. The evolution of meningococcal strains with genosubtype 19–54 should be closely monitored, as it might confer a greater transmission capacity.

INTRODUCTION: In solid organ transplant (SOT) recipients, hepatitis E virus (HEV) poses a complex clinical challenge, because there is a risk of developing persistent infection. Current European guidelines recommend the screening of HEV in SOT recipients because of the risk of unrecognised infection. Despite these recommendations, routine screening for HEV remains underutilised in clinical practice.

AIM: Our study aimed to determine the prevalence of HEV viraemia and to evaluate the clinical evolution of HEV infection in SOT.

METHODS: We performed a multicentre cross-sectional study including adult SOT recipients under follow-up in Spain. All patients were prospectively tested for HEV RNA in peripheral blood. Individuals with detectable viraemia were prospectively followed up every 3 months to evaluate viral persistence.

RESULTS: A total of 940 patients were included in the study. Five patients were infected, supposing a prevalence of HEV infection in Spanish SOT recipients of 0.53% (95% confidence interval: 0.23–1.24). Genotyping was successfully conducted in four cases, all identified as genotype 3. All patients were asymptomatic and had varied levels of liver enzyme elevations. At follow-up, three of the five patients remained HEC RNA-positive, consistent with chronic infection. Overall, the prevalence of chronic HEV infection in our study population was 0.32%.

CONCLUSION: Our study highlights the need to establish periodic molecular HEV surveillance in SOT recipients.

New and emerging infections with blood-borne pathogens pose an ongoing threat to the safety of blood transfusions and transplants. Bioarchives of stored blood donor samples represent a valuable pathogen screening resource for both ensuring safety of blood transfusions and for wider public health infectious disease surveillance. Large scale testing of donors enables early detection of pathogen spread and extent of population exposure. We have implemented two complementary systems for the bioarchiving of blood donor samples in England for these purposes. The CODONET bioarchive collects samples from geographically targeted regions of potential pathogen emergence. Consenting donors provide detailed information to allow for risk assessment and, importantly, to distinguish imported from autochthonously acquired infection. Separately, the blood donor surveillance archive (BDSA) stores 100 or 200 pools of 24 randomly selected, fully anonymised donation samples from donors in England every 2 weeks, allowing large-scale continuous sampling. This enables rapid evaluation of the presence of blood-borne pathogens in donor populations and a large-scale epidemiological tool to detect pathogen emergence in real-time. Combined, these bioarchives allow for proactive assessment of donation transmission risk, and as targeted population-wide archives, contribute to public health surveillance of emerging pathogens and pandemic spread.