Hepatitis B Vaccination among 1999⁻2017 Birth Cohorts in Zhejiang Province: The Determinants Associated with Infant Coverage.

This study aimed to investigate the coverage of hepatitis B vaccine (Hep B) and its completeness and timeliness for birth cohorts from 1999 to 2017 in Zhejiang province, East China. Demographic characteristics and vaccination records of Hep B of children born from 1 January 1999 to 31 June 2017 were extracted from the Zhejiang provincial immunization information system. The timeliness of the first dose of Hep B (Hep B1) was defined as the proportion of children who received the Hep B1 within 24 h after birth among the target population. The completeness of Hep B was defined as the proportion of children who completed the three-dose series of Hep B before 7 years of age. The demographic characteristics of the target population were described. The coverage of each dose of Hep B, the timeliness of Hep B1, and the completeness of Hep B for each birth cohort were described. A logistic regression model was applied to detect the determinants of the timeliness of Hep B1 and the completeness of Hep B vaccination. The coverage of Hep B1 increased from 90.3% to 98.3%, the coverage of Hep B2 increased from 88.8% to 96.1%, and the coverage of Hep B3 increased from 86.4% to 94.2%. The timeliness of Hep B1 increased from 80.3% to 91.3%. The completeness of Hep B increased from 81.3% to 91.5%. The determinants of timeliness of Hep B1 included children's delivery place, immigration status, maternal education level, and economic development level of resident area. The determinants of completeness of Hep B included children's delivery place, immigration status, maternal education level, economic development level of resident area, maternal occupation, and frequency of vaccination service. Zhejiang province had achieved significant improvements in the timely administration of Hep B1 and the completeness of Hep B. To accelerate progress toward additional reductions in the transmission of hepatitis B virus, further efforts need to be focused on improving the timeliness of Hep B1 vaccination and reducing the drop-outs among disadvantaged children with the risk factors identified in this study.