Hepatitis B antibody will bind to the hepatitis B virus when it meets the hepatitis B virus, and the memory B cells in the body will increase the hepatitis B antibody, and the hepatitis B antibody will not bind to other viruses when it meets other viruses, and the titer of the hepatitis B antibody will not increase. If there is hepatitis B antibody in the human body, it means that the human body has been vaccinated with hepatitis B vaccine or infected with hepatitis B virus, and if the titer of hepatitis B antibody is more than 100mIU/mL, the protection of the human body is relatively strong, and if the human body is re-infected with hepatitis B virus again, the hepatitis B antibody in the human body will neutralize the hepatitis B virus, and the memory B cells will activate rapidly and secrete a large amount of hepatitis B antibody. If the body is re-infected with other types of viruses, such as hepatitis A virus, then no matter what the titer of hepatitis B antibody is, the hepatitis B antibody will not neutralize the hepatitis A virus, and the memory B cells will not be activated and will not secrete hepatitis B antibody, so the hepatitis B antibody will not increase.