Serological changes against hepatitis B surface antigen in children and adolescents receiving chemotherapy for acute leukemia

Background: Vaccination for hepatitis B virus (HBV) after chemotherapy among pediatric patients with acute Leukemia is still a debated issue. We investigated HBV immunity before and after chemotherapy and assessed immune response to re-vaccination after chemotherapy. Methods: We retrospectively analyzed data of children and adolescents aged <19 years requested for vaccination after chemotherapy for acute leukemia to evaluate hepatitis B surface antibody (HBsAb) status before and after chemotherapy and to identify factors related to HBsAb positivity after chemotherapy. Results: Of 89 enrolled patients, 61 (68.5%) with acute leukemia were HBsAb positive before chemotherapy. Of these 61 patients, 48 (78.7%) seroconverted to HBsAb negative status after chemotherapy; there were 76 (85.4%) HBsAb negative patients after chemotherapy. HBsAb positive patients when compared to HBsAb negative patients after chemotherapy had a significantly higher HBsAb positive rate (100.0% vs. 63.2%, p=0.008) before chemotherapy. Following HBsAb testing after one dose of the HBV vaccination, 33 (43.4%) of the 76 HBsAb negative patients seroconverted to an HBsAb positive status. HBsAb positive patients after a single dose of HBV vaccination had a significantly higher HBsAb positive rate at the time of diagnosis compared to HBsAb negative patients (84.8% vs. 48.8%, p=0.001). Conclusions: Based on these results, HBV re-vaccination after chemotherapy is recommended for all children and adolescents with acute leukemia. In addition, further investigation is required to improve the immunogenicity of HBV re-vaccination.