The Immune Responses After Hepatitis B Revaccination Doses in a Young Cohort

This prospective cohort study aims to provide the evidence-based clinical guide to help decide the revaccination doses of hepatitis B vaccine that the high-risk young adults without hepatitis B seroprotective antibodies (anti-HBs titer\

Inclusion Criteria: 1. The actual age at the time of admission was higher than 20 years old and birth year after 1987 2. Born in Taiwan and had received a full course of hepatitis B vaccines at least three doses at infant period. 3. Those who have tested negative for hepatitis B surface antibody and surface antigen at baseline 4. Have never been vaccinated against hepatitis B in childhood and adolescence by questionnaire 5. Consent to administer 1-2 doses of hepatitis B vaccine according to the assigned group after sharing decision making process 6. In good health Exclusion Criteria: 1. Those who were previously allergic to hepatitis B vaccine or its components (such as yeast) 2. Those who have been vaccinated against hepatitis B during childhood and adolescence 3. Those who have a positive test for hepatitis B surface antibody or a positive test for hepatitis B surface antigen