Seroprevalence of anti-HBs antibodies and the need for booster vaccination in children under 5 years of age born to HBsAg-negative mothers

Objective:To determine the proportion of HBV surface antigen(anti-HBs)antibody positive children under five years of age born to HBs Ag-negative mothers and to analyze the possible related factors following implementation of a hepatitis B vaccination program for infants in Indonesia 22 years ago.Methods:Blood samples were taken from children under five years of age born to HBsAg-negative mothers who have completed primary vaccination series.Anti-HBs antibodies were determined by using rapid test.Data of age,gender,nutritional status,vaccination timing or vaccination compliance,and booster vaccination were collected from vaccination card.Results:Ninety children were enrolled,consisting of 47 females and 43 males with a mean age of 2.3 years.Twenty two(24.4%)children received booster vaccine between 18 and 24 months and 55(61.1%)were anti-HBs positive.Among factors of age,gender,nutritional status,compliance to vaccination and booster vaccine,only administration of booster vaccine was significantly associated with anti-HBs status(OR 5.45,95%CI 1.45,20.52).Children who received booster vaccine at age of 18-24 months were 5.45 times more likely to be anti-HBs positive than that of children who did not receive booster vaccine.Conclusions:Booster vaccine rate is low among children under 5 years of age but is associated with anti-HBs positivity.Booster vaccination may be required to improve anti-HBs seropositivity.