Adults need three injections of hepatitis B vaccine, and the situation after each injection is as follows: 1. After the first injection: only 30% of people can produce hepatitis B surface antibody, and the antibody is unstable; 2. After the second injection: 90% of people can produce hepatitis B surface antibody; 3. After the third injection: 96% of people can produce hepatitis B surface antibody, and The antibody can be maintained at a high level. The hepatitis B vaccination is to stimulate the body’s immune system to produce antibodies, which exist in body fluids and can clear the hepatitis B virus, and once the hepatitis B virus appears, it can stop the hepatitis B virus from infecting the human body, and it does not harm the liver, and it can play the role of immunity against the hepatitis B virus and play a protective role for the human body. Therefore, it is recommended that people who do not have hepatitis B surface antibody be vaccinated against hepatitis B.