Towards a Functional Cure for HBV - The COMMIT Cohort Study

Inclusion Criteria: * Male or female, aged 18 years and older * HIV antibody positive * Chronically-infected with HBV, as defined by: i. Positive Hepatitis B surface antigen HBsAg) or HBV DNA result with a subsequent positive HBsAg or HBV DNA result at least 6 months after first positive result (the 2nd HBsAg test may be taken at the baseline visit) ii. HBsAg positive with the absence of immunoglobulin M antibodies to HBV core at screening * Current or ever hepatitis C virus (HCV) antibody negative * Hepatitis D virus (HDV) negative * ART naïve or within 7-10 days of ART start at sites where immediate ART start (test and treat) is practice * Provide signed and dated informed consent form. * Willing to comply with all study procedures and be available for the duration of the study. Exclusion Criteria: * Hepatitis C virus (HCV) antibody positive * Hepatitis delta antibody positive * Anything that would place the individual at increased risk or preclude the individual's full compliance with or completion of the study.