[Hepatitis B surface antigen and antibody positive rates of children and adolescents in Jeju].

Background/aims: Korea has been an endemic area of Hepatitis B infection. Recently, the Hepatitis B carrier population has been significantly decreasing because of Hepatitis B vaccination. The aim of this study was to analyse the Hepatitis B surface antigen (HBsAg) and the Hepatitis B surface antibody (anti-HBs) positive rates of children and adolescents in Jeju.

Methods: From January 2000 to August 2002, seropositivity of HBsAg and anti-HBs were evaluated by enzyme immunoassay (EIA) in 1,653 pediatric patients. From April 2002 to August 2002, seropositivity of HBsAg and anti-HBs were evaluated by reversed passive hemagglutination (RPHA) in 2,532 students. From July 1994 to February 2003, seropositivity of HBsAg was evaluated by EIA in 1,013 pregnant women.

Results: The positive rates of HBsAg and anti-HBs of children and adolescents in Jeju were 2.1% and 70.9%, respectively. The positive rates of HBsAg of pregnant women in Jeju was 4.7% and that of HBeAg in HBsAg positive pregnant women was 38.1%. In children born after 1995, as age increased, HBsAg seropositivity increased significantly and anti-HBs seropositivity decreased significantly. There was no significant difference in testing HBsAg positivity between the RPHA and the EIA tests, but testing anti-HBs positivity by EIA was significantly higher than by RPHA.

Conclusions: To reduce HBsAg positive rate, regular testing for anti-HBs by EIA may be indicated until at least 15 years after the primary vaccination schedule, and booster vaccination may be indicated in subjects whose anti-HBs titer was under 10 mIU/mL. 29.1% of children and adolescents in Jeju, therefore, may need to be revaccinated.