Epidemiologic characteristics of hepatitis A before and after inclusion of hepatitis A vaccine into expanded program on immunization in Jinzhou, Liaoning, 2002–2019

ObjectiveTo understand the epidemiologic characteristics of hepatitis A in Jinzhou, Liaoning from 2002 to 2019 and before and after the inclusion of hepatitis A vaccine into the expanded program on immunization (EPI), and provide scientific evidence for the prevention and control of hepatitis A.

MethodsThe incidence data of hepatitis A in Jinzhou from 2002 to 2019 were collected for descriptive analysis on the epidemiological characteristics of hepatitis A before (2002–2007) and after (2008–2019) the EPI inclusion.

ResultsAfter the EPI inclusion, the annual average incidence rate of hepatitis A decreased from 6.24/100 000 to 2.42/100 000. Before the EPI inclusion, the incidence of hepatitis A in county towns was generally higher than that in central urban area. But after the EPI, except the higher incidence of hepatitis A in Yixian county, the area differences gradually decreased. With the exception of Kaifa district and Taihe district, the incidence of hepatitis A in each county (district) showed a downward trend, and there were significant difference before and after the EPI inclusion. The age distribution of the cases was unimodal. The incidence peaked in age group 30-years before the EPI inclusion and in age group 45-years after the EPI inclusion. The age with peak incidence showed an increasing trend. The constituent ratio of the cases in age groups 0-year and 15-years decreased significantly. The constituent ratio of the cases in age group 30-years and 60-years increased slightly, and the constituent ratio of the cases in age groups 45-years and ≥75 years increased significantly. More cases occurred in men than in women before and after the EPI inclusion. Before the EPI inclusion, the incidence peak in spring was obvious, but the sub peak in summer was not obvious. With the use of vaccine, the seasonal characteristics of hepatitis A gradually disappeared. The majority of the reported cases were farmers, housework/the unemployed people, workers. After the EPI inclusion, the case constituent of students and workers decreased significantly, and the case constituent of farmers, the retired, housework/the unemployed people increased significantly.

ConclusionAfter the EPI inclusion of hepatitis A vaccine, the incidence of hepatitis A gradually decreased in Jinzhou. In addition to routine vaccine immunizations, the results suggest that emergency vaccination needs to be carried out in the key areas and high-risk population. Mass vaccination of hepatitis A vaccine is the fundamental measure to increase the population immunity level.