•Primary Aim:
o To describe participants 6 months to \<18 years of age with hepatitis B virus (HBV) infection in a prospective cohort in the United States (US) and Canada and identify predictors of disease activation and progression
Secondary Aims:
* To describe clinical, virological, and immunological characteristics of participants with HBV in the US and Canada.
* To evaluate changes in HBV infection status and hepatitis B surface antigen (HBsAg) levels and factors associated with those changes.
* To verify whether a baseline HBsAg below 1,000 IU/mL and HBV DNA below 1,000 IU/mL is an accurate predictor of people who are, or who will become, inactive carriers, defined as people who are HBsAg positive, hepatitis B "e" antigen (HBeAg) negative, have normal alanine aminotransferase (ALT) and HBV DNA under 1,000 IU/mL on at least two occasions over a period of at least 6 months with HBV DNA under 1,000 IU/mL.
* To assess the health related quality of life (HRQOL) of treatment naïve hepatitis B surface antigen (HBsAg) positive children and adolescents
* To develop a bank of biospecimens (e.g., serum, plasma, DNA, liver tissue) obtained from participants with HBV infection.
* To identify pediatric participants from 2 years to \<18 years of age with chronic HBV infection for potential participation in treatment study to be conducted by the Hepatitis B Research Network (HBRN).
