A Phase 3, Open-label, Single-arm, Repeated-dose Study to Evaluate the Safety and Tolerability, Pharmacokinetics, and Antiviral Activity of Maribavir for the Treatment of Cytomegalovirus (CMV) Infection in Children and Adolescents Who Have Received a Hematopoietic Stem Cell Transplant (HSCT) or a Solid Organ Transplant (SOT)

Inclusion Criteria: * Parent/both parents or legally authorized representative (LAR) must provide signature of informed consent and there must be documentation of assent by the participant, as age appropriate, before completing any study-related procedures. * Be a male or female child or adolescent \< 18 years of age at the time of consent. For participants in Cohort 3 only (0 to \<6 years) must have a gestational age of at least 39 weeks and a minimum weight of 5 kg. * Be a recipient of an SOT or an HSCT that is functioning at the time of screening. * Have a documented CMV infection which ma…