title: A low rate of hepatitis B virus vaccine breakthrough infections in Mongolia.
abstract: A nation-wide hepatitis B virus (HBV) immunization program of all newborn babies was launched in Mongolia in 1991. However, the continuation of clinical icteric viral hepatitis infections in children led to the investigation to determine whether HBV breakthrough infections were occurring and if any were due to hepatitis B surface antigen (HBsAg) mutants. Hepatitis A virus (HAV) infections accounted for most of these cases with 3% of the jaundiced children shown to have acute hepatitis B. Hepatitis B vaccine protection was 93% against HBV infection and 97% against HBV carriage. A G145A "escape mutant" was found in one HBV carrier child only. Anti-HBs levels, however, were low with 85% having titers less than 100 IU/L, 46% of whom had levels less than 10 IU/L. The results from this study demonstrate that the HBV immunization program in Mongolia provides an effective level of protection. However, continued surveillance of breakthrough infections and close monitoring of "vaccine escape" mutants is required.
authors.affiliation: Department of Virology, Royal Free and University College Medical School, London, United Kingdom. samreen.ijaz@hpa.org.uk
authors.forename: Samreen
authors.initials: S
authors.lastname: Ijaz
authors.forename: Janchiv
authors.initials: J
authors.lastname: Khulan
authors.forename: Sara L
authors.initials: SL
authors.lastname: Bissett
authors.forename: R Bridget
authors.initials: RB
authors.lastname: Ferns
authors.forename: Pagbajabyn
authors.initials: P
authors.lastname: Nymadawa
authors.forename: Richard S
authors.initials: RS
authors.lastname: Tedder
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology* / Q000517:prevention & control* / Q000821:virology; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000235:genetics / Q000276:immunology; D017325:Hepatitis B Vaccines / Q000008:administration & dosage*; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology*; D006801:Humans; D017589:Immunization Programs; D007231:Infant, Newborn; D008986:Mongolia / Q000453:epidemiology; D015397:Program Evaluation
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines