The goal of this observational study is to learn about cytomegalovirus disease epidemiology in pediatric and adult liver transplant recipients in China. The main questions it aims to answer are:

• The incidence of Cytomegalovirus (CMV) Infections (including clinical significant CMV reactivations and CMV Diseases) among children and adults Liver transplantation patients in China
• All-cause Mortality (Survival probability at 1 year)
• Incidence of Allograft Rejection. Number of subjects with allograft rejection
• Graft Loss. Incidence of graft loss (re-transplantation)
• Late-onset CMV Disease. Incidence of late-onset CMV disease (occurring after 100 days post-randomization) as adjudicated by end point committee
• Bacterial Infections. Incidence of bacterial opportunistic infections
• Major Fungal Infections. Opportunistic fungal infections
• Major Non-CMV Viral Infections. Incidence of non-CMV viral infections We will collect demographic data of participants. All recipients and donors underwent preoperative testing for CMV pp65 antigenemia, plasma CMV DNA, and serum CMV antibody. All the recipients were followed up in a liver transplant follow-up clinic twice weekly for a month after discharge from hospital. After that, patients were followed up weekly for 3 months, fortnightly for 6 months, and monthly for 12 months.

Inclusion Criteria:

• Have received their first orthotopic liver transplant (the transplanted liver may be deceased donor or live donor graft) within 10 days prior.
• Children group: Age ≤18yeas；
• Adults group: Age >18yeas；
• Willingness to participate in the study
• Ability to understand information material
• Written informed consent

Exclusion Criteria:

• Have known Human immunodeficiency virus (HIV) infection (based on testing performed during the transplant evaluation process).
• Participation in another investigational agent trial
• Be undergoing multi organ transplant or have undergone prior organ transplant. Have expected life expectancy of less than 72 hours.

The participates had received their first orthotopic liver transplantation within 10 days prior. And there are no gender restrictions. The number of participants are 800.

A total of 1020 consecutive liver transplant recipients were screened for eligibility. Of these, 220 patients did not meet the inclusion criteria or declined to participate. Therefore, 800 patients were enrolled and constituted the study cohort.

From enrollment until end of follow-up, up to 12 months

As an observational study, the protocol did not mandate solicitation of all adverse events. However, mortality (all-cause death) and serious adverse events leading to hospitalization or graft loss were actively collected as part of the study outcomes. Other non-serious adverse events were not systematically collected.

The observational design, while reflecting real-world practice, introduces potential for confounding despite multivariate adjustment. Variations in immunosuppression protocols and CMV monitoring techniques across centers, though reflecting clinical reality, may have influenced outcomes. Additionally, the lack of systematic assessment of antiviral resistance and detailed immunological parameters limits our ability to explore mechanistic explanations for the observed findings.