HBV infection is prevalent worldwide, but the intensity of HBV infection varies greatly from region to region. According to the World Health Organization, about 2 billion people worldwide have been infected with HBV, of which 350 million are chronic HBV infected, and about 1 million people die each year from liver failure, cirrhosis and primary hepatocellular carcinoma (HCC) caused by HBV infection. 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 in 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 for blood donors, HBV infection caused by blood transfusion or blood products has been less frequent; transmission through 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 piercing, accidental exposure of medical personnel at work, sharing razors and toothbrushes, etc. can also be transmitted (III). (III) can also be transmitted. Mother-to-child transmission mainly occurs during the perinatal (labor) period, mostly through contact with the blood and body fluids of HBV-positive mothers during delivery (Ⅰ), 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 persons, especially those with multiple sexual partners (I). HBV is not transmitted through the respiratory and digestive tracts, so daily study, work or living contacts, such as working in the same office (including sharing office supplies such as computers), shaking hands, hugging, living in the same dormitory, eating in the same restaurant and sharing toilets without blood exposure, generally do not transmit HBV. epidemiological and experimental studies have not found that HBV can be transmitted through blood-sucking insects (mosquitoes, bedbugs, etc.).