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

Who May Qualify: 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 Who Should NOT Join This Trial: 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 Always talk to your doctor about whether this trial is right for you.