Hepatitis B virus (HBV) infection and chronic kidney disease (CKD) pose major global health challenges. CKD patients face a heightened risk of HBV infection, worsening their prognosis. This study evaluated the immune response to hepatitis B vaccination in CKD patients, the persistence of antibodies, and factors influencing vaccine efficacy. A retrospective study was conducted on 173 CKD patients (2014–2019) receiving routine vaccination at the Hospital Clínico Universitario de Valladolid, Spain. (ZIP Code:47003) Patients were immunized with Fendrix^® on a 0-1-2-6-month schedule, and verbal informed consent was obtained. A protective response was defined as Anti-HBs >10 IU/L, and a robust response as >100 IU/L. Overall, 90.8% achieved a protective response. Age was not a significant predictor (p = 0.137) between non-responders and protective or robust responders. 32.95% of patients died during follow-up. A robust response at the end of vaccination cycle was associated with higher antibody titers at 12 months (p = 0.002) but not at 24 (p = 0.550) or 36 months (p = 0.739). Kaplan–Meier analysis estimated median antibody duration as 26.5 months (Anti-HBs > 10 IU/L) and 25.4 months (Anti-HBs > 100 IU/L). A delay in vaccination compared to the recommended schedule was observed (one-sample Wilcoxon test, p < 0.001). Fendrix^® effectively induces protective immunity in CKD patients, but a robust early response does not ensure long-term persistence. The decline in antibody levels suggests the need for booster doses and periodic antibody monitoring to optimize long-term protection. Suboptimal vaccination adherence may reflect the inherent complexities of real-world clinical practice.

Background: Serological screening for HBV is standard in hemodialysis, and vaccination is recommended for non-immune patients. Objective: To determine the cause of positive HBsAg detected shortly after vaccination. Methods: We conducted a retrospective study in a tertiary hemodialysis unit. Patients with HBsAg reactivity after receiving the adjuvanted HBV vaccine (Fendrix^®) were followed with serial serology until HBsAg clearance. Results: Forty-four patients were monitored; seven (15.9%) tested HBsAg-positive 1–7 days post-vaccination, with no evidence of acute hepatitis, prior HBV infection, transplantation, or chronic immunosuppression. Six cleared HBsAg on repeat testing; one remained positive until day 19, with HBsAg as the only marker. Conclusions: Vaccine-related transient HBsAg antigenemia can occur shortly after immunization. Recognizing this phenomenon and timing routine serology appropriately can prevent misinterpretation and unnecessary workups in CKD patients.

Yellow fever remains a major public health threat in endemic and re-emerging regions of Africa and South America, with recent outbreaks highlighting persistent gaps in prevention and surveillance. Pregnant women represent a particularly vulnerable population, yet the epidemiology, clinical impact, and preventive strategies for yellow fever in pregnancy are insufficiently characterized. Physiological and immunological changes during gestation may influence host responses to infection; however, current evidence does not demonstrate increased susceptibility to or severity of yellow fever during pregnancy. Adverse materno-fetal outcomes, including miscarriage, stillbirth, preterm birth, and, in rare cases, perinatal transmission, have been reported but remain poorly characterized. Diagnostic challenges, overlapping clinical presentations with other arboviral and hepatic diseases, and limited access to specialized care further complicate clinical management in many endemic settings. This perspective provides a comprehensive overview of yellow fever in pregnancy during the 2024–2026 outbreak in the Americas, including a risk-stratification framework for prevention. We summarize current evidence on epidemiology, pathophysiology, diagnosis, and supportive care, and examine prevention strategies with particular emphasis on vaccination. Accumulated observational evidence and substantial real-world experience have not demonstrated an increased risk of serious adverse events and generally support the effectiveness of yellow fever vaccination during pregnancy when administered with appropriate clinical judgment. In high-risk settings, the benefits of maternal immunization clearly outweigh theoretical concerns, supporting a flexible, risk-based approach, despite relatively limited evidence. We also discuss national and international policies, post-pregnancy booster recommendations, and the importance of integrating vaccination assessment into antenatal care. Finally, we highlight critical knowledge gaps and research priorities, including the need for prospective registries and strengthened pharmacovigilance. Coordinated clinical and public health strategies are essential to protect maternal and neonatal health and to reduce the burden of yellow fever in endemic and re-emerging settings.

Introduction (Objectives): This study aimed to evaluate the serological response to a fourth dose of mRNA COVID-19 vaccine in patients with conditions that confer a high risk of severe disease, particularly those with high-level immunosuppression. Methods: An observational study was conducted at the Ramón y Cajal University Hospital between February and August 2022. Adults (≥18 years) with high-risk conditions who had received four doses of either BNT162b2 or mRNA-1273 were included. Anti-spike IgG levels were measured ≥14 days post-vaccination. An adequate response was defined as an antibody concentration ≥260 BAU/mL. Results: A total of 943 patients were analyzed; 846 (89.7%) achieved an adequate response. In the bivariate analysis, patients aged 60–74 years had a higher risk of inadequate response compared to those aged 18–39 years (OR 1.824 vs. OR 0.257). Female sex was associated with a higher risk of inadequate response (OR 1.522; 95% CI: 0.974–2.371). In multivariable logistic regression, patients with high immunosuppression had a higher, though not statistically significant, risk of inadequate response compared with those without. Discussion: Our findings are consistent with international evidence suggesting that age and certain clinical factors reduce vaccine immunogenicity. The observed paradoxical effect of sex could reflect the higher prevalence of aggressive immunosuppressive therapies among women in the study cohort. Conclusions: Most immunosuppressed patients achieved seroconversion after the fourth dose. These results underscore the need for tailored vaccination strategies and additional measures in highly immunosuppressed subgroups.

Introduction: Vaccination is a cornerstone of public health; however, the master’s-level training in Spain remains fragmented and largely delivered through non-official master’s degrees (Spanish título propio ) with heterogeneous structures and uneven coverage of critical domains. The lack of harmonized competency standards limits workforce readiness and international comparability. This study aimed to map the national training landscape and develop a consensus-based, competency-oriented core curriculum for a future official master’s program in vaccinology. Methods: We conducted a nationwide systematic environmental scan (May–June 2025) of master’s programs using official registries (RUCT, ANECA) and university websites. Eligible programs were required to be active in 2025–2026 and to have a publicly available syllabus. Two reviewers independently screened records and extracted data on European Credit Transfer and Accumulation System (ECTS) credits, delivery format, practicum and thesis requirements, tuition, language, and stated competencies. We then conducted a modified Delphi with a multidisciplinary expert panel. Consensus on the final domains was defined as a mean score of ≥4 (on a Likert scale of 1–5) and ≥80% agreement among participants. The agreed domains and their proposed ECTS allocations were compiled into a core curriculum worth 60 ECTS. Results: Of 20 records identified, 7 programs met the inclusion criteria. Only one—the Erasmus Mundus LIVE (Leading International Vaccinology Education)—was an official master’s degree (state-regulated, RUCT/ANECA-accredited; 120 ECTS); the remaining programs were university-awarded, non-official master’s degrees (24–60 ECTS). The majority of these programs were delivered online, primarily in Spanish; total tuition ranged from €560 to €10,159. All programs covered scientific fundamentals, epidemiology, and translational research; however, the inclusion of topics such as regulation/pharmacovigilance, health economics, risk communication, vaccine confidence, special populations, and internships was inconsistent. Four programs required a master’s thesis; only one offered professional internships (LIVE; 3 ECTS). The Delphi process produced an eight-domain framework with competency-based learning outcomes and 60 ECTS distributed across domains. Discussion: Spain’s master’s-level vaccinology education is heterogeneous, with gaps in regulatory science, economics, cross-cutting competencies (leadership, communication, ethics, and equity), special-population vaccination, and experiential training. A shared, competency-based framework can guide program redesign, enhance transparency for learners and employers, and support quality assurance and international alignment. Conclusion: We propose a Delphi-informed, eight-domain, 60-ECTS core curriculum to harmonize master’s-level vaccinology education in Spain, strengthen workforce preparedness, and align national training with international expectations.

Yellow fever remains a major public health threat in endemic and re-emerging regions of Africa and South America, with recent outbreaks highlighting persistent gaps in prevention and surveillance. Pregnant women represent a particularly vulnerable population, yet the epidemiology, clinical impact, and preventive strategies for yellow fever in pregnancy are insufficiently characterized. Physiological and immunological changes during gestation may increase susceptibility to severe disease and contribute to adverse maternal and fetal outcomes, including miscarriage, stillbirth, preterm birth, and, in rare cases, perinatal transmission. Diagnostic challenges, overlapping clinical presentations with other arboviral and hepatic diseases, and limited access to specialized care further complicate clinical management in many endemic settings. This perspective provides a comprehensive overview of yellow fever in pregnancy during the 2024–2026 outbreak in the Americas, including a risk-stratification framework for prevention. We summarize current evidence on epidemiology, pathophysiology, diagnosis, and supportive care, and examine prevention strategies with particular emphasis on vaccination. Accumulated observational evidence and substantial real-world experience have not demonstrated an increased risk of serious adverse events and generally support the effectiveness of yellow fever vaccination during pregnancy when administered with appropriate clinical judgment. In high-risk settings, the benefits of maternal immunization clearly outweigh theoretical concerns, supporting a flexible, risk-based approach, despite relatively limited evidence. We also discuss national and international policies, post-pregnancy booster recommendations, and the importance of integrating vaccination assessment into antenatal care. Finally, we highlight critical knowledge gaps and research priorities, including the need for prospective registries and strengthened pharmacovigilance. Coordinated clinical and public health strategies are essential to protect maternal and neonatal health and to reduce the burden of yellow fever in endemic and re-emerging settings.