My body tested negative for both halves of hepatitis B, and the doctor suggested an injection. What do you mean, half?

The spherical particles of hepatitis B virus have three components, and the human body will produce three kinds of antibodies accordingly, which should be called three pairs, but the core antigen can not be detected in the blood, so only five items are called hepatitis B two-and-a-half test. All negative results show that there is no infection, but there is no protective antibody in the body, which belongs to the susceptible population and needs hepatitis B vaccine. Hepatitis B surface antibody has a protective effect at birth. In order to maintain the antibody level, it is necessary to strengthen the injection every three years.