Effectiveness and safety of immunization with live-attenuated and inactivated vaccines for pediatric liver transplantation recipients

Background: Liver transplantation recipients are at high risk for severe complications due to infections because of being treated with immunosuppressive drugs that affect the immune system. Vaccination for liver transplantation candidates is generally recommended before surgery, but the opportunities for vaccination prior to transplantation in pediatric candidates are often limited by severe disease conditions. Methods: The participants in this study comprised 39 pediatric recipients of living donor liver transplantation performed between 2005 and 2013. Criteria for administering live-attenuated (measles, rubella, mumps, and varicella) and inactivated (hepatitis B, pertussis, and Japanese encephalitis) vaccines were as follows: (1) >1 year after transplantation; (2) no use of systemic steroids to treat acute rejection within the last 6 months; (3) serum trough concentration of tacrolimus <5. ng/mL; (4) no severe immunosuppression according to blood examinations; and (5) provision of written informed consent. Median age at transplantation was 17 months, and median period from transplantation to the beginning of immunization was 18 months. Results: Seroprotection rates for measles, rubella, mumps, varicella, hepatitis B, pertussis, and Japanese encephalitis after post-transplant immunization were 44% (11/25), 70% (19/27), 48% (12/25), 32% (6/19), 83% (19/23), 87% (13/15), and 88% (7/8), respectively. Seroprotection rates for measles, rubella, mumps, and varicella after second vaccination for recipients with primary vaccine failure after first vaccination were 100% (8/8), 50% (1/2), 71% (5/7), and 50% (5/10), respectively. While four recipients contracted mumps and eight contracted varicella before immunization, one recipient developed varicella after immunization. No serious systemic adverse events were observed in vaccinated recipients. Conclusions: Seroprotection rates for measles, mumps, and varicella appeared low in children after the first post-transplantation vaccination. Immunizations with four live-attenuated and three inactivated vaccines were safe and effective for pediatric liver transplantation recipients who were not severely immunosuppressed.