{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T17:38:24Z","timestamp":1787593104609,"version":"build-2736575974"},"reference-count":24,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2025,7,31]],"date-time":"2025-07-31T00:00:00Z","timestamp":1753920000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background: The 2022 conflict in Ukraine triggered mass migration, leading to a significant influx of Ukrainian refugee children into Poland. This situation raises concerns about hepatitis B virus immunity, as Ukraine\u2019s hepatitis B vaccination coverage has been inconsistent compared to Poland\u2019s high vaccination rates. Objective: To evaluate hepatitis B immunity and infection prevalence among Ukrainian refugee children residing in Southern Poland and to assess implications for vaccination strategies in the host country. Methods: A prospective cross-sectional study was conducted on 1322 Ukrainian refugee children (0\u201318 years) presenting to a pediatric infectious diseases department in Southern Poland between February 2022 and March 2024. Data on vaccination history, demographic characteristics, and selected laboratory parameters, including hepatitis B surface antigen and anti-HBs antibody levels, were collected. Protective immunity was defined as anti-HBs antibody levels \u226510 IU\/L. Results: Among the participants (mean age 9.9 years; 50.2% female), 83.2% were reported as vaccinated according to national immunization programs, but only 64.9% demonstrated protective anti-HBs antibody levels. Protective antibody prevalence declined significantly with age, with less than half of adolescents aged 15\u201318 years showing immunity. Five children (0.4%) were diagnosed with chronic hepatitis B, four of whom were unvaccinated. Conclusions: This study identifies a significant gap in hepatitis B immunity among Ukrainian adolescent refugees residing in Southern Poland, with less than half possessing protective anti-HBs antibody levels. This immunity gap and the high risk of sexual transmission of the hepatitis B virus in adolescents highlight the urgent need for comprehensive surveillance, screening, and catch-up vaccination programs.<\/jats:p>","DOI":"10.3390\/vaccines13080816","type":"journal-article","created":{"date-parts":[[2025,8,6]],"date-time":"2025-08-06T15:09:53Z","timestamp":1754492993000},"page":"816","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Low Hepatitis B Immunity Among Ukrainian Refugee Children and Adolescents in Poland: Need for Targeted Screening and Vaccination"],"prefix":"10.3390","volume":"13","author":[{"given":"Lidia","family":"Stopyra","sequence":"first","affiliation":[{"name":"Department of Infectious and Tropical Diseases, Andrzej Frycz Modrzewski Krakow University Medical College, 30-705 Krak\u00f3w, Poland"},{"name":"Department of Infectious Diseases and Pediatrics, Zeromski Specialist Hospital, 31-913 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karolina","family":"Banach","sequence":"additional","affiliation":[{"name":"Department of Infectious and Tropical Diseases, Andrzej Frycz Modrzewski Krakow University Medical College, 30-705 Krak\u00f3w, Poland"},{"name":"Department of Infectious Diseases and Pediatrics, Zeromski Specialist Hospital, 31-913 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Magdalena","family":"Wood","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases and Pediatrics, Zeromski Specialist Hospital, 31-913 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Justyna","family":"Stala","sequence":"additional","affiliation":[{"name":"Department of Infectious and Tropical Diseases, Andrzej Frycz Modrzewski Krakow University Medical College, 30-705 Krak\u00f3w, Poland"},{"name":"Department of Infectious Diseases and Pediatrics, Zeromski Specialist Hospital, 31-913 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Merklinger-Grucha\u0142a","sequence":"additional","affiliation":[{"name":"Department of Bioinformatics and Public Health, Andrzej Frycz Modrzewski Krakow University Medical College, 30-705 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,31]]},"reference":[{"key":"ref_1","unstructured":"(2024, August 19). 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Soc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"e2022388","DOI":"10.1001\/jamanetworkopen.2020.22388","article-title":"Prevalence of Hepatitis B Vaccination Coverage and Serologic Evidence of Immunity Among US-Born Children and Adolescents From 1999 to 2016","volume":"3","author":"Le","year":"2020","journal-title":"JAMA Netw. 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