Hepatitis B virus is spread one by one and the infection is usually scattered in the population. The hepatitis B virus does not become violently epidemic like the influenza virus, but it has a tenacious life force and a hidden transmission mechanism, and such a scattered occurrence one by one has accumulated 120 million infections in our country as well. Who can transmit hepatitis B to others? An infected person who can transmit the hepatitis B virus to others is called an “infectious agent”. The degree of contagiousness depends on the level of the virus in the blood. Chronic hepatitis B virus carriers with “major triple-positive” status have active virus replication and high levels of virus in their blood, making them the most active source of infection; carriers with “major triple-positive” status who are hidden in the population and have not yet been detected have the highest potential infectivity. However, not all people with hepatitis B virus are infectious. Chronic hepatitis B carriers with “minor triple-positive” have the virus in their liver, but the replication level is very low, and the hepatitis B virus is not detected in the serum, so they are less infectious. The size of the infectiousness has nothing to do with the level of serum aminotransferase, as it is the virus, not the aminotransferase, that is infectious. The size of the infectious source’s potential for transmission also depends on his work or lifestyle and how closely he comes into contact with others. By what means does an infected person with an infectious disease spread to others? Daily contact with carriers is not contagious. Transmission requires certain routes, mainly blood transmission, sexual contact and mother-to-child transmission. Hepatitis B virus is a blood-borne virus, and blood is required as a carrier for different transmission routes. Our blood transfusion management is very strict in recent years, blood transfusion transmission has been very rare; currently more common is the “micro blood inoculation”, such as tattoos, eyebrow tattoo, shaving, drug use, etc., because the infection is hidden and do not know. Imagine a street shaver’s razor is contaminated, it will spread to how many people? If a hair salon beauty store is contaminated with a tattoo needle, how many women will be infected? As for contaminated acupuncture needles from a clay doctor, it can even cause a small epidemic! Mother-to-child transmission used to be the most important route, which has been largely blocked due to the widespread vaccination against hepatitis B. Close contact transmission in daily life is mainly due to contact with objects contaminated by the patient’s blood, such as skin abrasions and sores of carriers of “major triple-positive”, releasing a large amount of hepatitis B virus to contaminate the surface of the environment, which can survive for a long time in vitro and then be infected by the broken skin of susceptible people. Infection from mucosal injury during sexual intercourse. In Europe and the United States sexual contact is the most important way of adult hepatitis B virus transmission; in our country hepatitis B can not yet be considered a sexually transmitted disease. What are the most common ways of transmission of hepatitis B virus in our society today? Although carriers of “major triple-positive” are highly infectious, they must be transmitted through certain channels (blood as a carrier), and general interpersonal contact is not infectious.