Initiation and completion rates of inactivated hepatitis A vaccination among children born between 2005 and 2014 in Zhejiang province, east China

Objectives: To evaluate the initiation and completion and timeliness of inactivated hepatitis A vaccine (HAV-I) series, to identify the missed opportunities for HAV-I series, and to examine determinants associated with the completion of HAV-I.
Methods: Children born from 1 January 2005 to 31 December 2014 and registered in Zhejiang provincial immunization information system (ZJIIS), were enrolled in this study. Descriptive statistics were used to describe the initiation and completion, the timeliness and the missed opportunities for HAV-I. Logistic regression analysis was applied to explore the determinants of the completeness of HAV-I.
Results: The initiation rate of HAV-I increased from 8.1% for the 2005 birth cohort to 13.2% for the 2014 birth cohort. The completion rate of HAV-I increased from 4.2% for the 2005 birth cohort to 7.8% for the 2014 birth cohort. The timeliness rate of the 1^{st} dose of HAV-I increased from 38.2% for the 2005 birth cohort to 57.9% for the 2014 birth cohort. The timeliness rate the 2^{nd} dose of HAV-I increased from 17.3% for the 2005 birth cohort to 35.3% for the 2014 birth cohort. 78.3% of the children who did not initiated any hepatitis A vaccine, had at least one immunization clinic visit after their 18^{th} month of age. 36.0% of the children who received the 1^{st} dose of HAV-I but did not receive the 2^{nd} dose, had at least one immunization clinic visit after 6 months from the date of receiving the 1^{st} dose of HAV-I. The determinants including year of birth, socio-economic development level of municipals, place of delivery, receipt of MMR/VarV were associated with the completion of HAV-I series.
Conclusion: Although the initiation and completion of HAV-I series had improved in recent years, these indicators were still lower than those for other vaccines scheduled at the similar age. It is important for providers to identify every opportunity for HAV-I vaccination and to assure that children get protection from this vaccine-preventable disease.