Additional Study Information: This study evaluates whether odevixibat is safe and effective compared to placebo in children with biliary atresia who have recently undergone a Kasai procedure. This is a double-blind study, so the study doctors and the child/parent will not know whether the child is receiving odevixibat or placebo. Participation will involve several research visits over approximately a 2 year period. After completion of the study, participants may be eligible to join an extension study to receive "open-label" odevixibat through the study. If you have any questions regarding this study, please contact the Transplant Clinical Research Center (TCRC).