Hepatitis B vaccination is a reliable method of preventing hepatitis B. However, its protective effect is limited in duration. The higher the titer of hepatitis B surface antibody, the stronger the immunity and the longer the duration of immune protection. After 3 doses of hepatitis B vaccine, about 90% of the vaccinees will have positive surface antibodies against hepatitis B. However, the antibody titer will gradually decrease over time, and the antibody positivity rate will drop to about 74% in the third year. When the antibody titer is less than 10 IU/ml, we will lose immunity against hepatitis B and can no longer prevent the infection of hepatitis B virus. The antibodies produced after vaccination usually last about 12 years, but in a few people the antibodies disappear completely after 1 to 2 years. At present, there are two types of hepatitis B vaccines used in China: domestic and imported. Due to the different strains and culture processes, there are certain differences between domestic and imported hepatitis B vaccines in terms of the number of antibodies produced, the length of time of vaccination and the size of side effects. Therefore, in order to ensure the preventive effect, after receiving the hepatitis B vaccine, blood should be drawn and tested for hepatitis B dichotomy, if the hepatitis B antibody is positive, it means the vaccination is successful, otherwise it indicates that the vaccination has failed and the dose needs to be increased. In addition, the titer of hepatitis B surface antibody should be measured. If the antibody titer is 10-100mIU/m1, it is better to repeat the vaccination after 6 months; if the antibody titer is 101-1000mIU/ml, the antibody titer should be retested within 1 to 2 years after the first vaccination; if the antibody titer is 1001-10000mIU/ml, it should be retested within 2 to 4 years; when the antibody titer is greater than When the antibody titer is greater than 10000mIU/ml, it can be retested within 4-6 years; when the antibody titer is found to be lower than 10mIU/ml, the hepatitis B vaccination should be repeated. In this way, the antibody in the body can be maintained at an effective level for a long time to ensure that we do not get infected with hepatitis B and truly achieve the purpose of preventing hepatitis B. Therefore, hepatitis B vaccination can stimulate the body to produce surface antibodies and make the body gain immunity against hepatitis B. However, the validity of hepatitis B vaccination is not lifelong, but usually lasts for about 5 years. After receiving the hepatitis B vaccine, it is important to check the effect of vaccination and the antibody titer of hepatitis B. When the antibody titer is less than the protection value, it is necessary to replenish the vaccination in time.