title: Assessment of anti-HBs antigen in 6- to 9-year-old children routinely vaccinated via vaccination program in Iran.
abstract: OBJECTIVE
  To determine persisting antibody levels to hepatitis B virus (HBV) antigen in healthy children, aged 6-9 years, vaccinated at birth.
  
  
  METHODS
  Blood samples were collected from 374 vaccinated children (178 girls and 196 boys) and 57 unvaccinated children, attending Shiraz Primary School, Shiraz, Iran from September 2002 to April 2003. An HBV surface antibody (anti-HBs) was determined using enzyme-linked immunosorbent assay.
  
  
  RESULTS
  The anti-HBs titer was detected in 17% of the 8-year-old children, 7.7% of the 7-year-old children and 46.6% of the 6-year-old children. The decrease was greatest in the 9-year-old children; more than half (54.3%) had a titer of less than 10 IU/ml, indicating a decrease in antibody levels with increasing age/time. Conversely, more than 35% of the 6-year-old children had a titer greater than 150 IU/ml compared with 24, 12 and 7% of children at the age of 7, 8 and 9, respectively, whose antibody titer was less than 150 IU/ml.
  
  
  CONCLUSIONS
  Antibody titer declined with time. In comparison with other countries, the antibody titer in Iranian children was much lower.
authors.affiliation: Department of Bacteriology and Virology, Medical School, Shiraz University of Medical Science, Shiraz, Iran. hadina@sums.ac.ir
authors.forename: Nahal
authors.initials: N
authors.lastname: Hadi
authors.forename: Negin
authors.initials: N
authors.lastname: Hadi
mesh_terms: D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006509:Hepatitis B / Q000276:immunology / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006801:Humans; D017589:Immunization Programs; D007492:Iran / Q000453:epidemiology; D008297:Male; D013997:Time Factors
chemical_list: D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines