Background: China has long been with high Hepatitis B Virus(HBV) prevalence in the world. The HBV prevalence of people aged 1-59 decreased to less than 8% in 2006, and by 2020, HBsAg positive rate of children aged <5 decreased to less than <1% which was due to the free three-dose hepatitis B(HepB) immunization for newborns nationwide since 2002. Huangpu district was selected as one of the pilot areas for free Hep B vaccination in newborns since 1986, which formed an early protection in the population from mother-to-child transmission. However, the existed HBV infected people were still needed to be discovered, evaluated whether to receive antiviral therapies and intervened with health education in order to reduce the incidence of viral hepatitis related hepatocellular carcinoma (HCC) and also reach the goal to eliminate public health hazards of viral hepatitis by 2030.

Objective: To know HepB immunization status among people aged 1 to 69 in Huangpu district of Shanghai, and find out risk factors changes of HBV infection.

Methods: Cross-sectional study was applied to analyze the HepB immunization status and related risk factors by carrying out survey among 706 participants aged 1 to 69 years old. Blood samples were collected for detection of serological HBV markers including hepatitis B surface antigen(HBsAg), hepatitis B surface antibody(HBsAb) and hepatitis B core antibody(HBcAb). Participants with HBsAg positive were required to complete additional examinations such as alanine aminotransferase(ALT), aspartate aminotransferase(AST), total bilirubin, albumin, globulin, liver fibroscan and liver ultrasound.

Results: For participants aged 1 to 14, the positive rate of HBsAg, HBsAb and HBcAb was 0.00, 50.00 and 30.46%, respectively. The HBsAb positive rate reached a peak of 90.91% at 2 years old, and then showed a significant downward trend (χ² = 55.612, p < 0.001). All the participants have completed three-dose Hep B vaccination, however for the second dose, those who vaccinated 30 days later than the appointed time(aged one month) got higher HBcAb prevalence than those who vaccinated on time(χ² = 5.87, p = 0.015). Two mothers were found HBsAg positive, but there was no significant difference in children's HBcAb positive rates regardless of the mothers' HBsAg results. For participants aged 15 to 69, the positive rate of HBsAg, HBsAb and HBcAb was 4.21, 44.25 and 49.23%, respectively. Multivariate analysis for HBcAb positive among people aged 15 to 69 showed that age(50-69) and HBsAb positive were the risk factors for HBcAb positive(p < 0.05). Higher education was the protective factor for HBcAb positive(p < 0.05). After the screening for HBsAg, 22 participants were tested HBsAg positive and required additional examinations, and a total of 12 completed all the examinations. One participant was recognized as active HBV infection without antivirus treatment. Among the 12 participants, 2 have received antiviral treatment before and 4 had a history of HBV infection in family members.

Conclusion: In this study, HBsAg positive rate of those who aged 1 to 14 was 0.00%, which indicated that the HepB immunization has achieved a lot in protecting children from being infected. However, failing to get timely Hep B vaccination could be an influencing factor for HBcAb positive in children. As a result, additional tests for HBV DNA could be done to specify an HBV infection and more attention should be paid to the timeliness of Hep B vaccination in the next step. The HBcAb positive rate of people aged 1 to 69 was relatively higher than that of other provinces. Despite of the limited participants with full examinations, we should still put emphasis on HBV treatment and the possibility of transmission within families.