Prevention: (a) Hepatitis B vaccine prevention. Vaccination against hepatitis B is the most effective way to prevent HBV infection. The targets of hepatitis B vaccination are mainly newborns, followed by infants and young children, unimmunized people under 15 years of age and high-risk groups (such as medical personnel, people with frequent contact with blood, staff of childcare institutions, organ transplant patients, frequent recipients of blood transfusions or blood products, people with low immune function, people prone to trauma, family members of HBsAg-positive people, men who have sex with men or have multiple sexual partners and intravenous drug users). The hepatitis B vaccine is required to be administered for 3 weeks.) Three doses of hepatitis B vaccine are required for the whole course, according to the 0, 1 and 6 months procedure, i.e., after the first vaccination, the second and third doses are given at intervals of 1 month and 6 months. Hepatitis B vaccination for newborns should be given within 24 hours of birth, the earlier the better. The vaccination site is intramuscular in the lateral anterior gluteal muscle for newborns, and intramuscular in the middle deltoid muscle of the upper arm for children and adults. The blockage rate of hepatitis B vaccine alone to block mother-to-child transmission was 87.8% at the Department of Hepatology, Taihe County Hospital of Traditional Chinese Medicine, Huaide (II-3). For newborns of HBsAg-positive mothers, hepatitis B immunoglobulin (HBIG) should be administered as early as possible within 24 h after birth (preferably 12 h after birth) at a dose of ≥100 IU, along with 10 μg recombinant yeast or 20 μg Chinese hamster oocyte (CHO) hepatitis B vaccine at different sites, and the second and third doses of hepatitis B at 1 and 6 months of age, respectively. The effectiveness of blocking mother-to-child transmission is significantly improved by vaccination at 1 and 6 months (II-3). Alternatively, one dose of HBIG can be administered within 12 h of birth, followed by a second dose of HBIG 1 month later, and a 10 μg recombinant yeast or 20 μg CHO hepatitis B vaccine at different sites at the same time, with a second and third dose of hepatitis B vaccine given at 1 and 6 months intervals, respectively. Newborns were allowed to receive breastfeeding from HBsAg-positive mothers after HBIG and hepatitis B vaccine were administered within 12 h of birth (III). Newborns of HBsAg-negative mothers can be immunized with 5 μg or 10 μg yeast or 10 μg CHO hepatitis B vaccine; children who did not receive hepatitis B vaccine as newborns should be given a catch-up dose of 5 μg or 10 μg recombinant yeast or 10 μg CHO hepatitis B vaccine; for adults, 20 μg yeast or 20 μg CHO hepatitis B vaccine is recommended. For those who are immunocompromised or non-responders, the vaccination dose (e.g. 60 μg) and number of doses should be increased; for those who do not respond to the 3-dose immunization program, 3 more doses can be given, and the anti-HBs in the serum should be tested 1~2 months after the second 3-dose hepatitis B vaccine, and if there is still no response, a 60 μg recombinant yeast hepatitis B vaccine can be given. The protective effect of hepatitis B vaccination for those with antibody response generally lasts for at least 12 years, therefore, anti-HBs monitoring or booster immunization is not required for the general population. However, anti-HBs monitoring can be performed in high-risk groups, and booster immunization can be given if anti-HBs is <10 mIU/mL (III). (ii) Cut off the transmission route. Vigorously promote safe injections (including needles for acupuncture) and strictly follow the Standard Precaution principle in hospital infection management. Haircutting, shaving, pedicure, piercing and tattooing instruments used in the service industry should also be strictly sterilized. Pay attention to personal hygiene and do not share razors and dental equipment with anyone. Provide proper sex education. If the sexual partner is HBsAg positive, he/she should be vaccinated against hepatitis B or use condoms; always use condoms to prevent hepatitis B and other blood-borne or sexually transmitted diseases when the health status of the sexual partner is unknown. For HBsAg-positive pregnant women, avoid amniocentesis and shorten the delivery time to ensure the integrity of the placenta and minimize the exposure of the newborn to maternal blood. (C) HBV prophylaxis after accidental exposure. After accidental exposure to the blood and body fluids of HBV-infected patients, the following methods can be followed: 1. Serological testing HBV DNA, HBsAg, anti-HBs, HBeAg, anti-HBc, ALT and AST should be tested immediately and retested within 3 and 6 months. 2. Active and passive immunization If hepatitis B vaccine has been given and anti-HBs ≥10 mIU/mL is known, special treatment may not be required. If you have not received hepatitis B vaccine, or if you have received hepatitis B vaccine but anti-HBs <10 mIU/mL or the level of anti-HBs is unknown, you should immediately inject HBIG 200-400 IU and receive one dose of hepatitis B vaccine (20g) at different sites at the same time, and receive the second and third doses of hepatitis B vaccine (20g each) 1 and 6 months later, respectively. (iv) Management of patients and carriers. When acute or chronic hepatitis B is diagnosed, it should be reported to the local Center for Disease Control and Prevention as required, and family members of the patient should be recommended to be tested for serum HBsAg, anti-HBc and anti-HBs, and those who are susceptible (those who are negative for these 3 markers) should be vaccinated against hepatitis B. The infectivity of hepatitis B patients and carriers depends mainly on the level of HBV DNA in the blood, but not on serum ALT, AST or bilirubin levels. Follow-up of patients and carriers of hepatitis B is described in this guideline under "Patient Follow-up". For chronic HBV carriers and HBsAg carriers, except for those who cannot donate blood, tissues and organs, and those who are engaged in occupations or jobs specified by the state, they can work and study as usual, but they should be followed up regularly.