{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T19:19:42Z","timestamp":1772133582107,"version":"3.50.1"},"reference-count":31,"publisher":"Public Library of Science (PLoS)","issue":"2","license":[{"start":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T00:00:00Z","timestamp":1772064000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100006492","name":"Division of Intramural Research, National Institute of Allergy and Infectious Diseases","doi-asserted-by":"publisher","award":["R01AI148049"],"award-info":[{"award-number":["R01AI148049"]}],"id":[{"id":"10.13039\/100006492","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100006492","name":"Division of Intramural Research, National Institute of Allergy and Infectious Diseases","doi-asserted-by":"publisher","award":["R37AI179640"],"award-info":[{"award-number":["R37AI179640"]}],"id":[{"id":"10.13039\/100006492","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec001\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Because of its low cost and lasting effects, hepatitis B virus (HBV) vaccination of adults in Africa could significantly contribute to viral elimination. Among at-risk adult populations there are few data to inform vaccine implementation, including on pre-existing immunity and vaccine uptake. We serologically profiled adults with specific risk factors for HBV infection in urban Zambia and evaluated their uptake of vaccine.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>At a tertiary hospital in Lusaka, we recruited hepatitis B surface antigen-negative adult (age 18+) contacts to people with chronic HBV, health workers (HCWs), and people with HIV (PLWH). After we jointly collected blood and gave the first HBV vaccine dose (blind to the full serological profile), we called back those whose results showed insufficient surface antibodies (anti-HBs) to complete the 3-dose series at 1 and 6 months, and we reimbursed transport costs. Stratified by group, we described the proportions of participants with past vaccination, resolved infection (anti-HBc-positive regardless of anti-Hbs status), isolated core antibodies (anti-HBc-positive and anti-HBs-negative), and neither antibody. We described the correlates of resolved infection. We described completion of the vaccine series in anti-HBs-negatives. In those with isolated core antibodies, we explored the incidence of an anamnestic response based on post-first-dose anti-HBs\u2009&gt;\u200910 IU\/ml and&gt;= 1-log increase from baseline.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>616 adults (median age, 32.2 years, IQR [26.7\u201343.8]; 61.2% women) enrolled, including 333 contacts, 213 HCWs, and 70 PLWH. Half had neither antibody, including 68.5% of health workers. Prior vaccination was seen in 8.3% overall, including 11.3% of HCWs. Resolved infection was present for 39.3% and was more prevalent with increased age and among contacts. Isolated core was present in 59 (9.6% overall and 24.7% of those with resolved infection) participants. Among the 383 participants eligible for vaccination, 377 (98.4%) received 1 dose, 190 (49.6%) received 2 doses, and 54 (14.1%) completed the series. Among 18 individuals with isolated core antibodies, none had detectable HBV DNA, and 9 (50%) had an anamnestic response.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>Most adults at risk for HBV in Lusaka, Zambia, had inadequate immunity, which could undermine HBV elimination. High resolved infection rate in contacts supports the role of index testing in HBV case finding. Low vaccine completion, despite vaccine access and addressing transportation costs, was striking and underscores the need for integrated behavioral science approaches to improve implementation of this potentially cost-effective intervention. Low rates of anamnestic response in people with anti-HBc-positivity should be further studied in Africa.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0339690","type":"journal-article","created":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T18:43:03Z","timestamp":1772131383000},"page":"e0339690","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Hepatitis B immunity and vaccine completion among adults at increased risk for hepatitis B infection in Zambia"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-8372-1131","authenticated-orcid":true,"given":"Enock","family":"Syabbalo","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sydney","family":"Mpisa","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael J.","family":"Vinikoor","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mercy","family":"Wamundila","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Likando","family":"Munalula","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Taonga","family":"Musonda","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ruth","family":"Phiri","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paul","family":"Kelly","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chloe","family":"Thio","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David L.","family":"Thomas","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Edford","family":"Sinkala","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2026,2,26]]},"reference":[{"key":"pone.0339690.ref001","volume-title":"Global hepatitis report 2024 action for access in low- and middle-income countries","author":"World Health Organization","year":"2024"},{"issue":"8","key":"pone.0339690.ref002","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1038\/s41575-023-00760-9","article-title":"Global burden of hepatitis B virus: current status, missed opportunities and a call for action","volume":"20","author":"Y-C Hsu","year":"2023","journal-title":"Nat Rev Gastroenterol Hepatol"},{"key":"pone.0339690.ref003","article-title":"Viral Hepatitis Scorecard","volume-title":"African Hepatitis Summit","author":"World Health Organization","year":"2019"},{"issue":"4","key":"pone.0339690.ref004","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1016\/S2468-1253(23)00315-1","article-title":"Under-representation of the WHO African region in clinical trials of interventions against hepatitis B virus infection","volume":"9","author":"M Delphin","year":"2024","journal-title":"Lancet Gastroenterol Hepatol"},{"issue":"5","key":"pone.0339690.ref005","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1002\/hep.1840010502","article-title":"A controlled clinical trial of the efficacy of the hepatitis B vaccine (Heptavax B): a final report","volume":"1","author":"W Szmuness","year":"1981","journal-title":"Hepatology"},{"key":"pone.0339690.ref006","doi-asserted-by":"crossref","DOI":"10.1093\/infdis\/jiaa668","article-title":"Hepatitis B Vaccines","volume":"224","author":"J Pattyn","year":"2021","journal-title":"The Journal of Infectious Diseases"},{"issue":"27","key":"pone.0339690.ref007","first-page":"369","article-title":"Hepatitis B vaccines: WHO position paper \u2013 July 2017","volume":"92","author":"World Health Organization","year":"2017","journal-title":"Weekly Epidemiological Record"},{"issue":"3","key":"pone.0339690.ref008","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1007\/s15010-008-7410-y","article-title":"Criteria for successful hepatitis B vaccination in adults: results of a case study","volume":"37","author":"F Hofmann","year":"2009","journal-title":"Infection"},{"issue":"1","key":"pone.0339690.ref009","doi-asserted-by":"crossref","DOI":"10.1093\/ofid\/ofw253","article-title":"Hepatitis B Virus Incidence and Risk Factors Among Human Immunodeficiency Virus-1 Negative Men Who Have Sex With Men in Kenya","volume":"4","author":"E Wahome","year":"2016","journal-title":"Open Forum Infect Dis"},{"issue":"3","key":"pone.0339690.ref010","doi-asserted-by":"crossref","first-page":"244","DOI":"10.1016\/j.jiph.2012.02.005","article-title":"Risk of bloodborne pathogen exposure among Zambian healthcare workers","volume":"5","author":"EK Phillips","year":"2012","journal-title":"J Infect Public Health"},{"key":"pone.0339690.ref011","doi-asserted-by":"crossref","first-page":"4851","DOI":"10.1016\/j.vaccine.2018.06.043","article-title":"Hepatitis B vaccination coverage among health-care workers in Africa: A systematic review and meta-analysis","volume":"36","author":"A Auta","year":"2018","journal-title":"Vaccine"},{"key":"pone.0339690.ref012","volume-title":"Implementation Framework & Clinical Guidance for Viral Hepatitis Prevention & Treatment","author":"Ministry of Health Zambia","year":"2019"},{"key":"pone.0339690.ref013","article-title":"Significance of anti-HBc only in blood donors: a serological and virological study after hepatitis B vaccination","author":"G Gessoni","year":"2014","journal-title":"Blood Transfus"},{"issue":"2","key":"pone.0339690.ref014","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/S2468-1253(16)30076-0","article-title":"Significance of anti-HBc alone serological status in clinical practice","volume":"2","author":"Q Wang","year":"2017","journal-title":"Lancet Gastroenterol Hepatol"},{"issue":"3","key":"pone.0339690.ref015","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1007\/s11901-020-00522-0","article-title":"Hepatitis B Core Antibody: Role in Clinical Practice in 2020","volume":"19","author":"RG Gish","year":"2020","journal-title":"Curr Hepatology Rep"},{"issue":"7","key":"pone.0339690.ref016","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1111\/imcb.12280","article-title":"Immunological memory","volume":"97","author":"JR Kirman","year":"2019","journal-title":"Immunol Cell Biol"},{"issue":"2","key":"pone.0339690.ref017","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/j.jinf.2012.03.009","article-title":"Immune response to hepatitis B vaccination in HIV-positive adults with isolated antibodies to HBV core antigen","volume":"65","author":"C Kaech","year":"2012","journal-title":"J Infect"},{"issue":"27","key":"pone.0339690.ref018","doi-asserted-by":"crossref","first-page":"4034","DOI":"10.1016\/j.vaccine.2012.04.031","article-title":"Significance and anamnestic response in isolated hepatitis B core antibody-positive individuals 18 years after neonatal hepatitis B virus vaccination in Taiwan","volume":"30","author":"FH Su","year":"2012","journal-title":"Vaccine"},{"key":"pone.0339690.ref019","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1186\/1471-2334-13-218","article-title":"Determinants of suboptimal hepatitis B vaccine uptake among men in the Republic of Korea: where should our efforts be focused: results from cross-sectional study","volume":"13","author":"B Park","year":"2013","journal-title":"BMC Infect Dis"},{"issue":"10","key":"pone.0339690.ref020","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0241226","article-title":"Full-dose hepatitis B virus vaccination coverage and associated factors among health care workers in Ethiopia: A systematic review and meta-analysis","volume":"15","author":"N Awoke","year":"2020","journal-title":"PLoS One"},{"issue":"4","key":"pone.0339690.ref021","article-title":"Completion of three-dose hepatitis B vaccination cycle and associated factors among health care workers in the Greater Accra Region of Ghana","volume":"19","author":"VE Senoo-Dogbey","year":"2024","journal-title":"PLoS One"},{"issue":"4","key":"pone.0339690.ref022","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1016\/j.ypmed.2013.04.013","article-title":"A randomised controlled trial of financial incentives to increase hepatitis B vaccination completion among people who inject drugs in Australia","volume":"57","author":"L Topp","year":"2013","journal-title":"Prev Med"},{"issue":"1","key":"pone.0339690.ref023","doi-asserted-by":"crossref","first-page":"920","DOI":"10.1186\/s12889-020-09032-6","article-title":"High level of vaccination and protection against hepatitis B with low rate of HCV infection markers among hospital health care personnel in north of Iran: a cross-sectional study","volume":"20","author":"S Hiva","year":"2020","journal-title":"BMC Public Health"},{"issue":"4","key":"pone.0339690.ref024","doi-asserted-by":"crossref","DOI":"10.1093\/ofid\/ofae150","article-title":"Hepatitis B Virus prevalence and transmission in the households of pregnant women in kinshasa, democratic Republic of Congo","volume":"11","author":"CE Morgan","year":"2024","journal-title":"Open Forum Infect Dis"},{"issue":"2","key":"pone.0339690.ref025","first-page":"98","article-title":"Hepatitis B infection is highly endemic in Uganda: findings from a national serosurvey","volume":"9","author":"J Bwogi","year":"2009","journal-title":"Afr Health Sci"},{"key":"pone.0339690.ref026","volume-title":"Abbott PRISM hepatitis B virus core antigen (E. coli, recombinant). 6E66","author":"P Abbott"},{"issue":"6","key":"pone.0339690.ref027","doi-asserted-by":"crossref","first-page":"591","DOI":"10.5144\/0256-4947.2013.591","article-title":"Isolated hepatitis B core antibody positive among vaccinated cohort in Malaysia","volume":"33","author":"SA Hudu","year":"2013","journal-title":"Ann Saudi Med"},{"issue":"1","key":"pone.0339690.ref028","doi-asserted-by":"crossref","first-page":"62","DOI":"10.3390\/biom15010062","article-title":"HBV cccDNA: The Molecular Reservoir of Hepatitis B Persistence and Challenges to Achieve Viral Eradication","volume":"15","author":"A Boonstra","year":"2025","journal-title":"Biomolecules"},{"issue":"1","key":"pone.0339690.ref029","doi-asserted-by":"crossref","first-page":"1164","DOI":"10.1186\/s12889-023-16108-6","article-title":"World Hepatitis day 2021 -screening and vaccination against Hepatitis B virus in Accra, Ghana","volume":"23","author":"KA Kusi","year":"2023","journal-title":"BMC Public Health"},{"issue":"2","key":"pone.0339690.ref030","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0281256","article-title":"Sero-prevalence of hepatitis B virus and compliance with hepatitis B vaccination schedules among outpatient clinic attendees in Nairobi","volume":"18","author":"B Langat","year":"2023","journal-title":"PLoS One"},{"key":"pone.0339690.ref031","article-title":"Hepatitis B serostatus and vaccine uptake and efficacy among health workers in Zambia","author":"W Kawana","year":"2022"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0339690","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T18:43:10Z","timestamp":1772131390000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0339690"}},"subtitle":[],"editor":[{"given":"Livia Melo","family":"Villar","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2026,2,26]]},"references-count":31,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,2,26]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0339690","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,26]]}}}