title: Assessment of hepatitis B vaccine-induced seroprotection among children 5-10 years old in Ulaanbaatar, Mongolia.
abstract: Hepatitis B virus infection is a serious public health problem. Mongolia is one of the countries with the highest rates of hepatitis B virus infection in the world. The routine immunization with the hepatitis B vaccine began nationwide in 1991. The purpose of this study was to determine the persistence of seroprotection (anti-HBs >or= 10 mlU/mL) in children 5-10 years old that were immunized with the hepatitis B vaccine as infants. In total, 438 children were selected from six health facilities in Ulaanbaatar through a multistage random sampling method. Vaccination information was confirmed by checking the vaccination records kept in the health facilities. A blood sample was obtained from each child for anti-HBs, HBsAg and anti-HBc. Of 438 children, five (1.1%) were HBsAg positive and 58 (13.2%) were anti-HBc positive. Sixty infected children were excluded and a total of 378 (86.3%) sera were evaluated. The seroprotective antibodies were detected in only one-fourth of the children at the age of ten. Titres of anti-HBs decreased significantly with age (Linear regression p = 0.01). This decrease is primarily due to the rapid decrease in children living in ger areas (p < 0.001) compared to children living in apartment areas (p = 0.152). On the other hand, children living with higher socio-economic status had more exposure to blood-borne pathogens, probably due to inappropriate health-seeking behaviors.
authors.affiliation: Department of Health Policy and Planning, School of International Health, Graduate School of Medicine, the University of Tokyo, Japan.
authors.forename: Tumendemberel
authors.initials: T
authors.lastname: Ochirbat
authors.forename: Moazzam
authors.initials: M
authors.lastname: Ali
authors.forename: Nymadawa
authors.initials: N
authors.lastname: Pagbajab
authors.forename: Lkhagva-Ochir
authors.initials: LO
authors.lastname: Erkhembaatar
authors.forename: Enkhtuya
authors.initials: E
authors.lastname: Budbazar
authors.forename: Naryad
authors.initials: N
authors.lastname: Sainkhuu
authors.forename: Erkhembaatar
authors.initials: E
authors.lastname: Tudevdorj
authors.forename: Chushi
authors.initials: C
authors.lastname: Kuroiwa
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006509:Hepatitis B / Q000276:immunology* / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000097:blood* / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008986:Mongolia
chemical_list: D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines