{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T12:41:07Z","timestamp":1782996067696,"version":"3.54.5"},"reference-count":43,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,9,30]],"date-time":"2025-09-30T00:00:00Z","timestamp":1759190400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.mdpi.com"],"crossmark-restriction":true},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: Hepatitis B virus (HBV) remains a persistent challenge for transfusion safety. Although testing for hepatitis B surface antigen (HBsAg) and nucleic acid testing (NAT) reduces transmission risk, antibodies to hepatitis B core antigen (anti-HBc) and antibodies to hepatitis B surface antigen (anti-HBs) provide additional insight into past infection and vaccine-induced immunity. We aimed to determine their seroprevalence among blood donors in southern Croatia and assess associations with age, occupation, and time since vaccination. Methods: This cross-sectional study was conducted between February and November 2024 at two regional transfusion centers in southern Croatia. A total of 1008 voluntary blood donors, all HBsAg- and NAT-negative, were tested for anti-HBc and anti-HBs using chemiluminescent microparticle immunoassay. Demographic and vaccination data were collected through verified medical records. Results: Anti-HBc was detected in 0.5% of donors, exclusively among the unvaccinated. Protective anti-HBs levels were found in 38.1% overall and 70.6% of vaccinated donors, with significant declines by age and more than 15 years post-vaccination (p = 0.024). Healthcare workers showed higher seroprotection than non-healthcare donors (67.0% vs. 35.1%; p &lt; 0.001), although one-third still lacked protective levels. Conclusions: HBV exposure was rare, but waning vaccine-induced immunity was evident, with protective anti-HBs levels in 70.6% of vaccinated donors, declining with age and time since vaccination. These findings highlight the need for periodic monitoring of anti-HBs and targeted booster strategies, especially in older and occupationally exposed groups. HBsAg and NAT provide a high level of transfusion safety, while the role of routine anti-HBc testing in this low-endemic context should be carefully evaluated in view of its potential benefits and drawbacks. Donor-based surveillance is a valuable tool for evaluating long-term vaccine effectiveness and guiding public health policy.<\/jats:p>","DOI":"10.3390\/vaccines13101027","type":"journal-article","created":{"date-parts":[[2025,10,1]],"date-time":"2025-10-01T07:58:13Z","timestamp":1759305493000},"page":"1027","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Hepatitis B Serological Immunity and Exposure Among Blood Donors in Southern Croatia: A Cross-Sectional Study"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-7364-7490","authenticated-orcid":false,"given":"Admir","family":"Dilberovic","sequence":"first","affiliation":[{"name":"Department of Transfusion Medicine, Dubrovnik General Hospital, 20000 Dubrovnik, Croatia"},{"name":"Faculty of Health Studies, University of Mostar, 88000 Mostar, Bosnia and Herzegovina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mirela","family":"Radman-Livaja","sequence":"additional","affiliation":[{"name":"Department of Transfusion Medicine, University Hospital Split, 21000 Split, Croatia"},{"name":"Faculty of Health Sciences, University of Split, 21000 Split, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0497-1333","authenticated-orcid":false,"given":"Ivana","family":"Talic-Drlje","sequence":"additional","affiliation":[{"name":"Department of Transfusion Medicine, University Hospital Mostar, 88000 Mostar, Bosnia and Herzegovina"},{"name":"Faculty of Medicine, University of Mostar, 88000 Mostar, Bosnia and Herzegovina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ana","family":"Stanic","sequence":"additional","affiliation":[{"name":"Department of Medical Biochemistry Laboratory, Karlovac General Hospital, 47000 Karlovac, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marina","family":"Njire-Braticevic","sequence":"additional","affiliation":[{"name":"Department of Laboratory Diagnostics, Dubrovnik General Hospital, 20000 Dubrovnik, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nikolina","family":"Tomicic","sequence":"additional","affiliation":[{"name":"Department of Laboratory Diagnostics, Dubrovnik General Hospital, 20000 Dubrovnik, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7674-6795","authenticated-orcid":false,"given":"Jurica","family":"Arapovic","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, University of Mostar, 88000 Mostar, Bosnia and Herzegovina"},{"name":"Center for Disease Control and Geohealth Studies, Academy of Sciences and Arts of Bosnia and Herzegovina, 71000 Sarajevo, Bosnia and Herzegovina"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1111\/cei.13614","article-title":"Therapeutic vaccination for treatment of chronic hepatitis B","volume":"205","author":"Cargill","year":"2021","journal-title":"Clin. 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