Study to Evaluate Efficacy, Safety and Biomarkers of Bulevirtide Treatment in Chronic Hepatitis D Patients

Inclusion Criteria: 1. Age \> 18 years 2. Diagnosis of chronic HBV/HDV co-infection. 3. Have compensated liver disease (presence of portal hypertension without ongoing hepatic decompensation as ascites, variceal bleeding and hepatic encephalopathy allowed). 4. Have indication for treatment of BLV, or already treated with BLV. 5. For female\* participants: 1. Postmenopausal for at least one year, or 2. Surgically sterile (total hysterectomy or bilateral oophorectomy, bilateral tubal ligation, staples, or another type of sterilization), or 3. Abstinence from heterosexual intercourse throughout the treatment period, or 4. Willingness to use highly effective contraception (double barrier method or barrier contraception in combination with hormonal or intrauterine contraceptive) throughout the treatment period and for 6 months after last dose of the drugs in the study. 6. Male participants must agree to use a highly effective contraception (double barrier method or barrier contraception in combination with hormonal or intrauterine contraceptive used by female partners) throughout the treatment period and for 6 months after last dose of the drugs in the study. 7. Participants who are willing to give written informed consent Exclusion Criteria: 1. Any contra-indications to treatment with BLV, including any intolerance or hypersensitivity to the active ingredient or other components of BLV. 2. Pregnant or breast-feeding women. 3. Patients with predictable difficulties of follow-up according to the investigator. 4. Any other condition that, in the opinion of Investigator, precludes the patient from taking part in this study.