Improved Sensitivity Detection of Serum HBsAg and HBsAg Reversion

Inclusion Criteria: * HBsAg-negative by Abbott's HBsAg Test and HBeAg-negative; * Having serum specimens retained at baseline and at 48 weeks off treatment follow up; * Being willing to follow up regularly for 1 year. Exclusion Criteria: * Patients with hepatitis B cirrhosis in the compensated and decompensated stages: this includes patients with a clear history of cirrhosis (imaging or histological evidence) or Child-Pugh score ≥5 prior to NUC treatment, or who have had complications of the decompensated stage of cirrhosis, such as ascites, hepatic encephalopathy, or ruptured oesophago-gastric fundal varices bleeding; * Combined HAV, HCV, HDV, HEV, HIV infections, alcoholic liver disease, inherited metabolic liver disease, pharmacological liver disease, non-alcoholic fatty liver disease, autoimmune liver disease and other chronic liver diseases; * Primary hepatocellular carcinoma or those with AFP greater than 100 ng/ml at screening and imaging suggestive of possible malignant hepatic occupancy; or patients with AFP greater than 100 ng/ml for a sustained period of 3 months; * Patients with a combination of other malignant tumours (excluding those who have been cured); * Patients with severe diseases or uncontrolled disease * Those who are also participating in other clinical studies; * Patients deemed unsuitable by the investigator to participate in this study.