Efficacy and Safety of Ricovir® in Maintaining Durability of Viral Response in Chronic Hepatitis B Patients Who Have Been Treated With Viread® and Have Undetectable HBV DNA in Serum

Ricovir® Group Inclusion Criteria: * Male or female aged more than 20 years old; * CHB patients who have been treated with Viread® for more than 1 year; * Serum HBV DNA level is undetectable (not detected or \<20 IU/mL) at screening; * Informed consent must be obtained before the commencement of any screening procedures or study drugs Exclusion Criteria: * Patients with active HCC or other types of malignancy; * Patients with impaired renal function (defined as eGFR ≦ 30 mL/min/1.73m2); * Patients with hepatitis A (HAV), hepatitis C (HCV), hepatitis D (HDV) or human immunodeficiency virus (HIV) coinfection; * Patients with alcohol dependence or addiction; * Patients with autoimmune hepatitis; * Patients with primary biliary cholangitis (PBC); * Pregnancy, planning on getting pregnant, or breast-feeding; * History of allergy, hypersensitivity, intolerance, or experiencing severe adverse reactions to tenofovir or any ingredient of the study drug; * Not suitable for participating in this trial at the investigator's discretion. Historical Control Group Eligible individuals will be obtained from the TCVGH historical database based on matching (1:1) in terms of age (±5 years) and gender. To be eligible for the study, subjects must meet all of the following criteria: * Male or female aged more than 20 years old; * CHB patients who had been treated with Viread® for more than 1 year; * Patients who had discontinued Viread® therapy for at least 24 weeks during the period from January 2014 to December 2021 and had undetectable HBV DNA (not detected or \<20 IU/mL) in serum at the time of discontinuation; * Patients who have the data of HBV DNA level 24 weeks after the time of discontinuation, with a time window of +4 weeks is allowed; * The informed consent requirement will be waived based on the approval of IRB.