Changes in seroprevalence of hepatitis A after the implementation of universal childhood vaccination in Shandong Province, China: A comparison between 2006 and 2014

[Display omitted] •Childhood vaccination against hepatitis A virus (HAV) in China has achieved a positive effect.•The age of the population susceptible to HAV has been shifted towards an older age group.•More attention should be paid to young adults.•Ongoing monitoring is important to determine the direction of vaccination policy. The hepatitis A vaccine (HepA) has been included in the national expanded program on immunization (EPI) in China since 2008. This study was performed to evaluate the change in dynamics of the seroepidemiology of hepatitis A virus (HAV) before and after the introduction of the program. The trends in seroepidemiology of anti-HAV antibodies were examined in Shandong Province, China, drawing on two population-based samples of persons aged 1–59 years, one obtained in the year 2006 (n = 6682) and the other in 2014 (n = 5095). A dramatic increase in seroprevalence of anti-HAV antibodies from 30.76% (95% confidence interval (CI) 26.24–35.28%) to 77.46% (95% CI 74.04–80.87%) among children aged 1.5–7 years (born after HepA was recommended for routine childhood immunization), as well as an increase from 35.32% (95% CI 29.31–41.33%) to 66.69% (95% CI 55.59–77.80%) in subjects aged 8–14 years, was observed in 2014 when compared with 2006. By contrast, a decline in seroprevalence among subjects aged 15–29 years, as seen particularly in those 20–29 years of age, from 85.72% (95% CI 80.29–91.14%) to 69.24% (95% CI 62.02–76.45%), was found in this study. There was no statistically significant difference in seroprevalence between 2006 and 2014 among the subjects older than 30 years of age. The national HepA routine immunization program has had a positive effect, leading to an increase in anti-HAV seroprevalence among children in Shandong Province, China. More attention should be paid to young adults in the province.