Effectiveness of hepatitis A immunization after pediatric liver transplantation: A retrospective observational analysis.

This retrospective study aimed to investigate the response to hepatitis A virus (HAV) immunization following liver transplantation. We analyzed 234 vaccination records of 284 children who underwent liver transplantation between January 2003 and July 2021, including annual serologic results. Of the 120 HAV-naïve patients, approximately 71% and 83% showed seroconversion after receiving 1 and 2 vaccine doses, respectively. The third dose increased the seroconversion rate to 93%. In multivariable logistic regression analysis, the number of vaccine doses and age at first vaccine dose were independently associated with seroconversion. In contrast, additional immunosuppression with mycophenolate mofetil was negatively associated with seroconversion. In Cox regression analysis, of all 96 seroconverted children, younger age at first vaccination and additional immunosuppression with either mycophenolate mofetil or prednisolone were identified as independent risk factors for the early loss of HAV immunity. In summary, HAV immunization with the 3-dose vaccination series is recommended for pediatric liver transplant recipients. Antibody testing and booster vaccinations, if necessary, are recommended, especially for those living in endemic areas or with additional immunosuppressive treatments.