Vaccinal Effect of HBsAg Monoclonal Ab VIR-3434 in Chronic Hepatitis B Infection [VISION]

Inclusion Criteria:

1. Age ≥ 18 to ≤65 years

2. Chronic HBV infection with evidence of HBsAg-positivity x > 6 months

3. Quantitative HBsAg 300 - 10,000 IU/mL

4. On stable nucleos(t)ide therapy >1 year

5. HBV DNA < 60 IU/mL on 2 occasions at least 12 weeks apart

6. ALT ≤ 45 U/L on 2 occasions at least 12 weeks apart

7. Female subjects must have a negative pregnancy test or confirmation ofpostmenopausal status. Women of child-bearing potential (WOCBP) must have a negativepregnancy test at screening and on Day 1, cannot be breast feeding, and must bewilling to use highly effective methods of contraception 14 days before study drugadministration through the study participation. Female subjects must also agree torefrain from egg donation and in vitro fertilization from the time of study drugadministration through the study participation.

8. Male subjects with female partners of child-bearing potential must agree to meet 1of the following contraception requirements from the time of study drugadministration through the study participation: documentation of vasectomy orazoospermia, or male condom use plus partner use of 1 of the contraceptive optionslisted for contraception for WOCBP. Male subjects must also agree to not donatesperm from the time of study drug administration through the study participation.

9. Able and willing to sign informed consent

Exclusion Criteria:

1. History of cirrhosis as evidenced by prior Liver Elastography (Fibroscan) > 12kilopascals (kPa), liver biopsy (F4 by METAVIR) or clinical evidence ofdecompensation (ascites, hepatic encephalopathy)

2. History of or current hepatocellular carcinoma

3. Hepatitis C Virus (HCV) RNA or anti-Hepatitis D Virus (HDV) positive

4. HIV co-infection

5. Pregnancy or lactation

6. Alanine Aminotransferase (ALT) > 45 U/L

7. History of chronic liver disease other than HBV aside from fatty liver documentedonly on US

8. Use of peginterferon therapy for HBV infection within past 12 months

9. Use of chronic immunosuppressive medications at a dose equivalent to 10 mg daily ofprednisone or greater within past 6 months

10. Other significant medical illness that might interfere with this study: significantpulmonary dysfunction in previous 6 months, malignancy other than non-melanoma skincancer in previous 5 years, immunodeficiency syndrome

11. Subject has received any investigational drug (including any investigationalvaccines) within 90 days or 5 half-lives (whatever is longer) before screening forthis study or is currently enrolled in an investigational study

12. Subject has any condition for which, in the opinion of the investigator,participation would not be in the best interest of the subject (eg, compromise thewell-being) or that could prevent, limit, or confound the protocol-specifiedassessments, such as liver FNAs

13. Platelet count < 120,000,000,000/L

14. The International Normalised Ratio (INR) > 1.3

15. Bilirubin > 40 µmol/L

16. Hemoglobin < 110 g/dL for women or 120 g/dL for men

17. estimated Glomerular Filtration Rate (eGFR) < 45 cc/min

18. Alpha Fetoprotein (AFP) > 50 ng/mL

19. Prior liver or other solid organ transplantation

20. Patients on anticoagulation therapy or with any bleeding diathesis

21. Patients with hemoglobinopathy (thalassemia, sickle cell disease etc)

22. Other significant liver disease: alcoholic liver disease, autoimmune hepatitis,hemochromatosis, primary biliary cholangitis, primary sclerosing cholangitis, WilsonDisease or alpha-1 antitrypsin deficiency - as documented in clinical history

23. Unable to provide informed consent