The second positive hepatitis B surface antibody indicates immunity to hepatitis B. After the hepatitis B virus attacks the body, the body’s immune cells react by producing hepatitis B surface antibodies, which have a neutralizing effect on the hepatitis B virus, and are therefore protective antibodies. The higher the value of this antibody, the stronger the immunity to hepatitis B. The reason for the appearance of this antibody is mainly twofold: 1) the body has been injected with the hepatitis B vaccine, and the body has produced protective antibodies under the stimulation of the hepatitis B vaccine; 2) the body has been infected with the hepatitis B virus, but it is an insidious onset, the body does not show any symptoms, but the antibodies produced by the immune system have destroyed the virus. In summary, the appearance of hepatitis B surface antibodies is a good phenomenon, it is recommended to have regular medical checkups, this antibody number does not exist for life, when the antibody value <10mIU/mL after regular injections of hepatitis B vaccine to stimulate the immune system again to produce higher protective antibodies.