Immunisation policies have strong influences on the epidemiology of hepatitis A and B infection. In Hong Kong, vaccines against both viruses have been available through different channels and programmes in the past 3 decades. To evaluate the changes in the prevalence of hepatitis A and B in the general population, a seroepidemiology study is conducted involving a prospective cross-sectional survey followed for serology testing. Eligible members of 1327 spatially random households would be invited to join the study by completing a questionnaire and providing blood samples, either by dried blood spots or venesection, for determining the presence of antigen and/or antibody against hepatitis B, as well as antibody against hepatitis A. The main measures comprise a set of metrics on the prevalence of hepatitis A and B. Analysis would be conducted to examine the association of risk factors with the tested markers and describe the attitudes towards viral hepatitis vaccination. The results would allow us to understand the transmission potential of hepatitis A and B in the community would be influenced by the changing disease epidemiology and coverage of vaccination, which inform the development of new vaccination strategies in Hong Kong

Inclusion Criteria:

• residents normally living in Hong Kong
• living in domestic households randomly selected from Building Groups
• Any age, while subjects below the age of 18 would require informed consent of their guardians for participation
• Any gender

Exclusion Criteria:

• unable to understand written Chinese or English,
• failure to give consent for participation
• living in institution or non-domestic housing,
• foreign domestic helpers,
• normally living in Hong Kong

Residents of Building Groups from diverse geographical locations in Hong Kong selected through cluster sampling are targeted. With the building information available, three households would be randomly selected from each Building Group.