Saliva from a person with major triple-positive hepatitis B is contagious because hepatitis B surface antigen can be detected in the saliva of a person with major triple-positive hepatitis B. However, the conditions for transmission are harsh. When a person is in a weakened immune system and comes into contact with the saliva of a person with hepatitis B, it is possible for that person to become infected with hepatitis B. The hepatitis B virus is transmitted mainly through the following channels: 1. mother-to-child transmission: a mother who is positive for the hepatitis B virus transmits the virus to her fetus or newborn during pregnancy, childbirth and breastfeeding; 2. blood and body fluid transmission: the infected person has a high level of hepatitis B virus in his blood, and a tiny amount of blood entering the susceptible person can cause infection, such as transfusion of blood products, surgery, needle stabbing, sharing razors or toothbrushes with a person infected with the virus, as well as blood dialysis, organ transplantation, etc. Sexual contact transmission: This refers to unprotected sexual contact with an infected person who is positive for the hepatitis B virus, resulting in the transmission of the virus. Patients with hepatitis B should actively go to the hospital for treatment, and those with serious conditions should be treated in isolation to prevent others from being infected. In addition, hepatitis B vaccination is the most crucial measure to prevent hepatitis B. The body should be checked regularly for protective antibodies, and if antibodies disappear, supplemental injections should be given in a timely manner. For mothers infected with hepatitis B during delivery, the newborn should be injected with hepatitis B immunoglobulin and hepatitis B vaccine immediately after birth and again after 1 month and 6 months to prevent the occurrence of infection.