Hepatitis B two. A positive second half indicates that protective antibodies to hepatitis B are present. The second item is hepatitis B surface antibody. Hepatitis B surface antibody is a protective antibody that is immune to hepatitis B virus and protects the body from hepatitis B virus infection. The higher the titer of hepatitis B surface antibody the better the protection for the human body. Hepatitis B surface antibody has good protection for the human body if it is higher than 100 IU. There are two ways to obtain hepatitis B surface antibodies: one is to produce hepatitis B surface antibodies after being infected with the hepatitis B virus, and the other is to obtain them through vaccination.