Hepatitis B virus (HBV) infection is a major public health problem facing the world, with more than 2 billion people infected with HBV. There are more than 400 million chronic carriers, and 75% of carriers live in the Asia Pacific region.

The mother-to-child transmission route of hepatitis B virus is recognized as one of the most important routes of transmission, and recent studies have found that fathers who are carriers of HBV may also be one of the risk factors for HBV infection in children, but as far as the investigators know. Therefore, as a high-population area in China, the purpose of this study is to investigate the prevalence of HBV infection in this population.

Hepatitis B virus (HBV) infection is a major public health problem facing the world, with more than 2 billion people infected with HBV. Although since 1986 the World Health Organization (WHO has reduced the incidence of hepatitis B virus-related chronic liver disease, cirrhosis and hepatocellular carcinoma by incorporating hepatitis B vaccination into routine vaccination programmes for infants and adolescents, There are more than 400 million chronic carriers, and 75% of carriers live in the Asia Pacific region. Occult hepatitis B virus infection (OBI) is HBV surface antigen negative, but HBV DNA can be detected by PCR. Although the clinical consequences of OBI have not yet been fully determined, recent studies have shown that OBI may cause HBV-related diseases such as hepatitis B, cirrhosis, hepatocellular carcinoma, or aggravation or aggravation, and patients who receive immunosuppression through organ or blood transfusion. OBI reactivation has occurred. The protective effect on humans after vaccination with hepatitis B vaccine has the investigator sakened over time, and anti-HBs-negative children may have a higher risk of HBV infection due to loss of protection.

The mother-to-child transmission route of hepatitis B virus is recognized as one of the most important routes of transmission, and recent studies have found that fathers who are carriers of HBV may also be one of the risk factors for HBV infection in children, but as far as the investigators know, only Studies in Taiwan and other places have reported studies on HBV infection in children with HBV-infected mothers, and no research has focused on the effects of fathers' HBV positivity on children. Therefore, as a high-population area in China, the purpose of this study is to investigate the prevalence of HBV infection in this population.

Inclusion Criteria:

• The father or (and) mother is HBV-infected (pre-pregnancy or present)；
• Children is vaccinated with hepatitis B vaccine after birth;

Exclusion Criteria:

• Children with HBV infection;
• Participants agreed to undergo clinical follow-up studies.

The father or (and) mother is a HBV-infected person (pre-pregnancy or present), who is vaccinated with hepatitis B vaccine.