Impacts of vaccination on hepatitis B viral infections in Korea over a 25-year period.

BACKGROUND Hepatitis B virus (HBV) vaccination has effectively reduced the acute and chronic infection rates in recent years. Since 1983, HBV vaccination has been recommended for all neonates in Korea. METHODS This article reviews the impacts of HBV vaccination throughout the past 25 years in Korea. Before the introduction of the HBV vaccination program, approximately 8% of the general Korean population tested positive for hepatitis B virus surface antigen (HBsAg). RESULTS The percentage of vaccinated infants has surpassed 98.9% since 1990. The HBsAg carrier rate in the general population decreased to 3.7% in 2007. In particular, the prevalence of HBsAg decreased to 0.44% in teenagers and to 0.2% in children younger than 10 years. In addition, administration of the HBV vaccine may have reduced the risk of hepatocellular carcinoma among adults. Despite the administration of hepatitis B immunoglobulin and the HBV vaccine to children with HBsAg-positive mothers, the failure rate of HBV immunoprophylaxis was 4.2% in 2008. In Korea, there have been no reported cases of HBV surface gene variants such as G145R. CONCLUSIONS The prevalence of HBV carriers in Korea was markedly reduced after the introduction of the universal HBV vaccination program. Korea is now classified as an area of intermediate endemicity for HBV.