Hepatitis A Vaccination Rates and Related Factors in a 2005 Population-based Study in Nonsan, Korea

Very low prevalence of anti-HAV in Japan: high potential for future outbreak

Since the early 21^st century, almost all developed countries have had a very low hepatitis A virus antibody (anti-HAV) sero-prevalence profile, as sanitation conditions and health care facilities have been optimized to a universal standard. There has not been a report on anti-HAV prevalence among a large scale population in Japan since 2003. Therefore, this study aimed to investigate the current HAV status among the general population in Hiroshima. From each age and sex specific group, a total of 1,200 samples were randomly selected from 7,682 stocked serum samples from residents' and employees' annual health check-ups during 2013-2015. Total anti-HAV was detected using Chemiluminescent Enzyme Immunoassay. The overall anti-HAV sero-prevalence was 16.8%. In both males and females, anti-HAV prevalence among individuals between 20-59 years of age was as low as 0.0-2.0%, whilst that among 70 s was as high as 70.0-71.0%. A large number of residents aged under 60 are now susceptible to HAV infection. The cohort reduction trend of anti-HAV in Japan exposes the high possibility of mass outbreak in the future. HAV vaccine especially to younger generation and high risk population may prevent outbreak in Japan.

Factors related to completed status and seropositivity of hepatitis a immunization among children aged 1-3 years and 6-8 years in South Korea

This study was designed to identify factors associated with hepatitis A immunization status and seropositivity in Korean children. In-person interviews, reviewing their vaccination cards and testing hepatitis A antibody were conducted with 389 children aged 1–3 years and 544 children aged 6–8 years. In all age groups, earlier birth order was the only significant factor in children receiving either single or both doses of the vaccination. And completion of the second dose of vaccination was a prerequisite for increased seropositivity. Additionally, household income had a positive impact on seropositivity only in children aged 6–8 years. Our findings suggest that presence of an economic barrier is the underlying cause of the decreased hepatitis A vaccination services in Korea. Therefore, hepatitis A vaccine should be included in the essential National Immunization Program.