The 2006 national epidemiological survey of hepatitis B showed that the HBsAg carriage rate of the general population aged 1-59 in China was 7.18%, and the HBsAg of children under 5 years old was only 0.96%. According to this projection, the existing chronic HBV infection in China is about 93 million people, including about 20 million cases of chronic hepatitis B patients. HBV is a blood-borne disease, mainly transmitted through blood (such as unsafe injection, etc.), mother-to-child and sexual contact. Due to the implementation of strict HBsAg screening of blood donors, HBV infection caused by blood transfusion or blood products has been less frequent; transmission by broken skin and mucous membranes is mainly due to the use of medical devices that are not strictly sterilized, invasive diagnostic and surgical operations, unsafe injections, especially drug injections; other things such as pedicures, tattoos, earring holes, accidental exposure of medical personnel at work, sharing razors and toothbrushes The transmission can also occur. Mother-to-child transmission mainly occurs during the perinatal (labor) period, mostly from contact with the blood and body fluids of HBV-positive mothers during delivery, but with the application of hepatitis B vaccine combined with hepatitis B immunoglobulin, mother-to-child transmission has been greatly reduced. The risk of HBV infection increases with unprotected sexual contact with HBV-positive people, especially those with multiple sexual partners. Epidemiological and experimental studies have not found that HBV can be transmitted by blood-sucking insects (mosquitoes, bedbugs, etc.).