A high prevalence of hepatitis B (HepB) antibody loss after liver transplantation (LT) and de novo HepB infection (DNH) was documented, hence revaccination to prevent DNH is crucial. This study aimed to compare the safety and immunogenicity of two HepB vaccine regimens in liver-transplanted children. Liver-transplanted children who were previously immunised but showed HepB surface antibodies (anti-HBs) ≤ 100 mIU/mL were randomised to receive a standard three-dose (SD) and double three-dose (DD) vaccine intramuscularly in months 0-1-6. Anti-HBs and T-cell-specific response to the HepB antigen were assessed. A total of 61 children (54.1% male, aged 1.32 ± 1.02 years) completed the study without any serious adverse reaction. The seroprotective rate was 69.6% vs. 60% (p = 0.368) and 91.3% vs. 85% (p = 0.431) in SD and DD after the first and third 3-dose vaccinations, respectively. The geometric mean titre (95% confidence interval) of anti-HBs in SD and DD were 443.33 (200.75-979.07) vs. 446.17 (155.58-1279.50) mIU/mL, respectively, at completion. Numbers of interferon-γ-secreting cells were higher in hyporesponders/responders than in nonresponders (p = 0.003). The significant factors for the immunologic response to HepB vaccination were anti-HB levels prevaccination, tacrolimus trough levels, and time from LT to revaccination. SD and DD had comparative immunogenicity and were safe for liver-transplanted children who were previously immunised.
Keywords: children; de novo hepatitis B; hepatitis B virus; immunization; liver transplantation; vaccine.