The most important transmission route for hepatitis B is mother-to-child transmission. If a mother has hepatitis B, her child has a very high chance of being born with hepatitis B. More than 60% of hepatitis B patients in China are infected through this route. In addition, blood transfusions and medical devices (acupuncture, injections, dental veneers, etc.) may also be a means of transmission. The main victims of hepatitis B transmission are infants and children, whose weak immune defenses are the main reason for their vulnerability to hepatitis B infection and its chronicity. The younger the age of hepatitis B infection, the more likely it is to become chronic, the more likely it is to develop liver fibrosis and cirrhosis, and the more difficult it is to treat. The hepatitis B virus is prevalent in places such as buses, hotels, restaurants and hospitals, and the chances of contracting hepatitis B are quite high. However, because the immune mechanism of the adult body is better, the chances of becoming a hepatitis B virus carrier or hepatitis B patient are much smaller than those of infants and children. This is the main reason why the spouses of hepatitis B patients are rarely infected with hepatitis B virus, but their children often suffer from hepatitis B. It is also the reason why about 70% of people in China have been infected with hepatitis B, but only about 10% of them eventually become hepatitis B patients or carriers. The hepatitis B vaccine is very effective in protecting infants and children from hepatitis B virus infection, but it must be used correctly, especially if the parents are hepatitis B virus carriers or hepatitis B patients, and it is very important to inject high-valent hepatitis B immunoglobulin at the same time, and to check whether hepatitis B surface antibodies are produced in time after the vaccination is completed, and to give a booster shot if necessary.