Hepatitis A vaccine immunogenicity among seronegative liver transplanted children.

The hepatitis A virus (HAV) vaccine is highly immunogenic in general, yet data on its use in liver-transplanted (LT) children is limited. This study aimed to determine the seroimmunity to HAV in all LT children, and the immunogenicity of an inactivated HAV vaccine in seronegative LT children at King Chulalongkorn Memorial Hospital. Seronegative LT children received the inactivated HAV vaccine at 0 and 6-8 months with adverse events monitored for 3 days post-immunization. The result reviewed that among 105 LT children, vaccination records were available for 81%, of which 7.1% and 16.5% with one and two doses of HAV vaccine were immunized before transplantation, respectively. Post-transplantation, 20.1% were seropositive for HAV, with 9.5% due to pre-transplant immunization. Eighty-three seronegative LT children (aged 7.25 ± 4.40 years; 48.6% male) received two vaccine doses. The seropositive rate increased following the first and second doses and reached to 51.5%, and 92.9%, respectively (p < 0.001), with no serious adverse events reported. Age at vaccination and the interval from transplantation to vaccination were risk factors for non-responsiveness (p < 0.001). The study highlighted inadequate HAV vaccination coverage, leaving most LT children susceptible to infection. HAV vaccine proved highly immunogenic and safe, emphasizing the need for improved vaccination strategies before and after liver transplantation.Trial registration TCTR20220110001.