CHARM: Chronic Hepatitis B Antihepadnaviral Resistance Mutation Study

Inclusion Criteria: * Aged 18 years and over * Provided informed consent * Diagnosis of chronic hepatitis B (HBsAg documented for at least 6 months) * Currently prescribed antihepadnaviral therapy (including, but not limited to: lamivudine, adefovir, entecavir, tenofovir or telbivudine) for chronic hepatitis B management * Been taking current antihepadnaviral therapy for at least 6 months prior to recruitment * Negative tests for HIV Ab, Hepatitis C Ab and Hepatitis D Ab within the previous 2 years Exclusion Criteria: * Known or suspected co-infection with HIV, Hepatitis C or Hepatitis D * Concomitant immunosuppression / immunomodulatory therapies * Diagnosis of hepatocellular carcinoma where anticipated life expectancy is less than 6 months * Current participation in an interventional, blinded, pharmaceutical industry-sponsored clinical trial * Current Child Pugh class C classification (current Child Pugh score \> 9) * Other known or suspected cause of chronic liver disease * Any other reason that, in the investigator's opinion, participation in the study would not be in the participant's best interest.