Entry criteria：1. Age 18 years and above. 2. male or female. 3. Diagnosed as chronic HBV infection (HBsAg positive) 4.Ability to sign informed consent.~Exclusion criteria：Patients who disagree to participate in the trial.~After the informed consent was signed, the quantitative data of the previous surface antigen or HBV DNA titer was collected during the return visit. 4 ml of venous blood was collected on the same day or the remaining serum from the surface antigen or hepatitis B quantitative test was collected for the detection of hepatitis D antibody and/or the quantitative detection of hepatitis D RNA.~After statistical analysis, calculate the hepatitis D infection status in China.
This cross-sectional study will screen out hepatitis D virus-infected patients in HBsAg-positive people. Observe and describe the prevalence of hepatitis D infection among HBsAg positive people. The provinces of China are divided into 5 geographical areas (North, South, East, West and Central) to recruit patients according to the population density of each area. After statistical calculation, the total number of population needed is 3808.