This is a multicenter, randomized, controlled Phase IIa study of HH-003 to evaluate the antiviral activity and safety in nucleos(t)ide analogues-treated chronic hepatitis B subjects with low-level viremia. HH-003 is a human monoclonal antibody targeting the pre-S1 domain of the HBV large envelope protein. It blocks engagement of preS1 with sodium taurocholate co-transporting polypeptide (NTCP), the cellular receptor for HBV.

Inclusion Criteria:

• Signed informed consent form;
• Male or female aged from 18 to 60 years (inclusively);
• 18 kg/m^2≤BMI≤30 kg/m^2, body weight≥50 kg for men and ≥45 kg for women;
• Subjects who have chronic HBV infection greater than or equal to 6 months at screening;
• 10 IU/mL≤HBsAg≤3000 IU/mL; HBV DNA≤2000 IU/mL; ALT≤3×ULN;
• Subjects who have been on nucleoside reverse transcriptase inhibitors therapy for more than 1 year prior to screening.

Exclusion Criteria:

• Females who are pregnant or lactating at screening;
• History of alcoholic liver disease, moderate fatty liver, autoimmune liver disease, other hereditary liver disease, drug-induced liver disease or other clinically significant chronic liver disease induced by non-HBV infection;
• History of cirrhosis at any time prior to or at time of screening, or having progressive liver fibrosis at screening ;
• History or evidence of hepatocellular carcinoma at any time prior to or at time of screening;
• Exclusionary laboratory results at screening: total bilirubin >2xULN or direct bilirubin >1.5xULN，hemoglobin <120 g/L for males or <110 g/L ro females，platelets count<100,000/mm^3 (100×10^9/L), and absolute neutrophils count <1,500/mm^3 (1.5×10^9/L).