title: Significance and anamnestic response in isolated hepatitis B core antibody-positive individuals 18 years after neonatal hepatitis B virus vaccination in Taiwan.
abstract: OBJECTIVE
  To investigate the significance of isolated hepatitis B core antibody (anti-HBc) and to analyze the response to hepatitis B virus (HBV) booster vaccination in young adults with isolated anti-HBc who had been fully vaccinated with HBV vaccine as infants.
  
  
  METHODS
  We screened 1734 new university entrants who had been fully vaccinated against HBV in infancy for the presence of hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), and anti-HBc upon university entry. Results positive for isolated anti-HBc were reconfirmed by testing for the presence of HBsAg and anti-HBc once more, and further evaluated for anti-HCV, anti-HIV, and HBV DNA status 6 months later. Students were also offered HBV booster vaccinations at that time. Geometric mean titers (GMT) of anti-HBs after one booster dose of HBV were compared between students with isolated anti-HBc and students with HBV naïve status.
  
  
  RESULTS
  The overall prevalence of isolated anti-HBc in our student cohort was 1.2% (21 of 1734). No evidence of occult HBV infection was observed. A "booster" anamnestic response (anti-HBs titer ≥ 10 mIU/mL) was noted in 95% (20 of 21) of subjects with isolated anti-HBc. After re-measurement of anti-HBc, 13 (62%) of the 21 subjects with isolated anti-HBc were reclassified as having resolved HBV infection with a loss of anti-HBs. In the remaining 8 subjects (38%), isolated anti-HBc was determined to be false positive. The HBV status of these 8 subjects was HBV naïve due to the waning-off effect of anti-HBs of the neonatal HBV vaccination. There was no significant difference in anamnestic response to a single HBV booster dose of vaccine between students with isolated anti-HBc (n=13) and those with HBV naïve (n=323) status (GMT 50.6 vs 47.7 mIU/mL, P=0.90).
  
  
  CONCLUSIONS
  The presence of isolated anti-HBc 18 years after HBV vaccination can be attributed to post-HBV infection with a loss of anti-HBs and to a decline in anti-HBs elicited by vaccine. A single HBV booster dose of vaccine is recommended for subjects with isolated anti-HBc who were fully vaccinated with HBV vaccine as infants. This finding needs to be replicated in further studies with larger cohorts.
authors.affiliation: School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan.
authors.forename: Fu-Hsiung
authors.initials: FH
authors.lastname: Su
authors.forename: Chyi-Huey
authors.initials: CH
authors.lastname: Bai
authors.forename: Fang-Yeh
authors.initials: FY
authors.lastname: Chu
authors.forename: Yu-Shiang
authors.initials: YS
authors.lastname: Lin
authors.forename: Chien-Tien
authors.initials: CT
authors.lastname: Su
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Yeh
mesh_terms: D005260:Female; D006509:Hepatitis B / Q000276:immunology / Q000517:prevention & control*; D006510:Hepatitis B Antibodies / Q000097:blood*; D006512:Hepatitis B Core Antigens / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary / Q000379:methods; D007156:Immunologic Memory; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D013624:Taiwan; D014611:Vaccination / Q000379:methods*; D055815:Young Adult
chemical_list: D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D017325:Hepatitis B Vaccines