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. HBsAg in children under 5 years old is only 1%. 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 (blood transfusion and blood products, broken skin and mucous membranes), 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 piercings, accidental exposure of medical personnel at work, sharing razors and toothbrushes can also be transmitted. Other factors such as foot massage, tattooing, earring piercing, accidental exposure of medical personnel at work, sharing razors and toothbrushes, etc. can also be transmitted. Mother-to-child transmission occurs mainly during the perinatal (labor) period, mostly from exposure to the blood and body fluids of HBV-positive mothers during delivery, and has been greatly reduced with the use of hepatitis B vaccine combined with hepatitis B immunoglobulin. 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.).