Fig. 1

Distribution of hepatitis B surface antibody titer group by age group (a) The positive rate was highest in the 0-year-old and 1-year-old age groups and the weakly positive rate was highest in the 2-year-old to 4-year-old age groups; the negative rate was highest thereafter. (b) In the most recent 24 months, antibody titer was categorized by month. Positive ratios were observed in at least 50% of children up to 16 months, and in less than 50% thereafter