China is a major hepatitis B country, but what exactly is hepatitis B? Many people do not know. Why do people get scared when they talk about “hepatitis B”? How scary is hepatitis B? I believe that only when you understand hepatitis B will you be able to face it openly and actively prevent it. The term “hepatitis B” usually refers to “viral hepatitis B”, which is a liver disease caused by hepatitis B virus (HBV) infection. Hepatitis B virus is present in the body fluids (mainly blood) of the infected person, and a healthy person may be infected through contact with the blood or other body fluids (skin secretions, semen, vaginal secretions) of the infected person through a break in the skin, or through contact with the hepatitis B virus through a break in the mucous membrane of the mouth or digestive tract (e.g., bite, inflammation, ulcer, etc.). The hepatitis B virus is usually transmitted from mother to newborn during childbirth, through injections without the use of disposable syringes and treatment equipment, through blood transfusions containing the hepatitis B virus, through unprotected sexual contact with an infected person, and so on. Hepatitis B virus is not transmitted through air, food and water, so it is not transmitted in daily life such as shaking hands, hugging and eating. In addition, even when infected with hepatitis B virus through the above-mentioned transmission channels, the amount of virus entering the body may be different. Blood transfusion is most likely to have more virus entering the body, so it is easy to show acute onset; followed by injection, therapeutic utensils and mother-to-child transmission; while the amount of virus infection from sexual and close life contact is very small. Therefore, the focus of infection prevention is on blood transfusion (blood products), injection, therapeutic appliances and mother-to-child transmission. The hepatitis B virus enters the body, and some infected people carry the virus for life without developing the disease; some infected people have a large proliferation of hepatitis B virus in their bodies under certain conditions, which destroys liver cells, so that hepatitis B occurs. Although people can’t exactly grasp when the latent virus proliferates and the rules that lead to the occurrence of hepatitis B, there are a few things that are certain, namely, the conditions under which the virus destroys liver cells: first, the virus is actively replicating (HBeAg positive, HBV-DNA positive); second, there are triggers for liver damage such as alcohol and medication; third, there are factors that break the balance between the immune system and the virus; fourth, the overlapping infection with other hepatitis viruses or HIV. Special attention should be paid to the fact that even though the hepatitis B virus is replicating in large numbers, the virus often quietly wreaks havoc, so most patients with hepatitis B have no obvious symptoms and only show mild-moderate elevations in transaminases over a long period of time. Therefore, people infected with the hepatitis B virus need to have their liver function and hepatitis B virus replication levels checked regularly and treated promptly once abnormal liver function is detected. The most effective measure to prevent and treat hepatitis B is hepatitis B vaccination. The hepatitis B vaccination generally requires three injections, with the first injection followed by a second injection at 30-day intervals and a third injection at five-month intervals. After the three injections are completed, the injector should go to a medical institution for a hepatitis B antibody test. If the test is positive, it means that there is resistance to the hepatitis B virus and the chance of being infected is greatly reduced; if the test is negative, then the hepatitis B vaccination should be continued until it is positive. I believe that only by understanding the enemy of hepatitis B can we “know ourselves and our enemy and win a hundred battles”.