There are five main ways of transmission of hepatitis B: First, mother-to-child transmission. Mother-to-child transmission includes two aspects, one is vertical transmission, and the other is horizontal transmission. People always think that mother-to-child transmission is vertical transmission, but it is not. Only 10% is caused by intrauterine transmission, and only 10% of the fetus is infected in the uterus during pregnancy, which is not very high. Mainly in horizontal transmission, which is in close contact during the perinatal period and after birth. As a "three-positive" mother, the probability of being infected after birth is 90%-95%, and the probability of children born to hepatitis B mothers with negative E antigen is half lower than that of mothers with positive E antigen, which is about 45%-40%. Second, iatrogenic infection. In the process of hospital examination and treatment, the repeated use of medical devices contaminated by HBV without strict disinfection led to infection. This is called iatrogenic transmission, including surgery, dental instruments, blood collection needles, acupuncture needles and endoscopes. Third, blood transfusion spread. Transfusion of blood and blood products infected by HBV can cause hepatitis B. Fourth, close contact and communication in life. Including eating together, as long as the skin and mucosa are damaged in life, they may be infected. After the skin and mucosa are damaged, the body fluids of hepatitis B patients may be infected if they fall into the damaged skin and mucosa. Using razors and toothbrushes in daily life can also cause HBV transmission, which is called close life infection. Fifth, sexual transmission. For patients with hepatitis B, it can be transmitted through sex, and sexual transmission is also a kind of body fluid transmission. In addition, kissing can also spread, and it is also possible if the oral mucosa is damaged. At present, mosquito bites are not considered as a route of infection. When I went to the infectious disease hospital to see a patient, I was scared by a mosquito bite, which was unnecessary.