Hepatitis B virus is present in the patient’s blood and various body fluids, including sweat, saliva, breast milk and vaginal secretions. Hepatitis B virus is transmitted mainly through the following four areas: 1) blood transmission, such as blood transfusion, use of blood products, use of contaminated syringes or needles, tooth extraction, surgery, hemodialysis, organ transplantation, as well as foot trimming, tattooing, ear piercing, etc. 2) mother-to-child transmission, through slight abruption of the placenta during pregnancy, contact of the baby with the mother’s blood, amniotic fluid or vaginal secretions through broken skin and mucous membranes during delivery, and breastfeeding after delivery. It can be transmitted through close contact in daily life, such as sharing toothbrushes and razors, etc. It can also be transmitted through sexual contact, as semen and vaginal secretions contain hepatitis B virus, so unprotected sexual contact can also be transmitted.