[Efficacy and safety of hepatitis B re-vaccination in children after completion of chemotherapy and(or) hematopoietic stem cell transplantation].

To assess the anti-hepatitis B surface antibody (HBsAb) titers in children after completion of chemotherapy and (or) hematopoietic stem cell transplantation (HSCT), evaluate the efficacy and safety of the current hepatitis B re-vaccination schedule. A total of 239 children who completed their chemotherapy and (or) HSCT and visited the vaccination clinic of Shanghai Children's Medical Center from March 2017 to July 2019 were enrolled in this study. According to the previous diseases, patients were divided into leukemia group (85 cases), lymphoma group (30 cases), solid tumor group (49 cases) and non-malignant hematological disease group (75 cases). According to the treatment of previous diseases, the patients were divided into chemotherapy group (126 cases), HSCT group (89 cases) and chemotherapy plus HSCT group (24 cases). HBsAb titers were assessed both at the time of diagnosis and after completion of treatment and some children who were HBsAb seronegative were re-vaccinated with 3 doses of hepatitis B vaccine, the vaccine-related adverse reactions were monitored. HBsAb titers were measured again one month after the completion of inoculation. HBsAb titers were defined as negative at levels <10 U/L and positive at ≥ 10 U/L. Chi-square test or Fisher exact test was used to compare the difference of negative conversion rate of hepatitis B antibody between groups, and Logistic regression was used to explore the risk factors of hepatitis B antibody negative conversion. Among 239 patients, there were 143 males and 96 females. At the time of diagnosis, 179 patients (74.9%) were HBsAb seropositive and 60 patients (25.1%) were HBsAb seronegative. After completion of chemotherapy and (or) HSCT, 133 of 179 children with HBsAb seropositive (74.3%) at diagnosis became HBsAb seronegative. Univariate analysis showed significant differences at the negative conversion rates of HBsAb between different disease groups (χ²=10.211，=0.015), different treatments groups (χ²=14.899，<0.01) and different HBsAb titers groups before treatment (χ²=32.117，<0.01). Logistic regression showed that HSCT (chemotherapy group as the reference, odds ratio (）=2.999, 95% confidence interval () 1.276-7.050，=0.012) and HBsAb titers<328.2 U/L before treatment (HBsAb titers≥328.2 U/L group as the reference, 6.397， 95% 3.159-12.954，<0.01) were risk factors for negative conversion of HBsAb. Among 48 patients whose HBsAb was seronegative after completion of chemotherapy and (or) HSCT and re-vaccinated with hepatitis B vaccine, 47 (97.9%) cases became HBsAb seropositivie. No serious adverse effects or complications were reported among these patients. After completion of chemotherapy and (or) HSCT, most children completely lose their protective humoral immunity against hepatitis B. Hepatitis B re-vaccination schedule can be efficiently and safely applied in those patients.