title: Immune responses of prematurely born infants to hepatitis B vaccination: results through three years of age.
abstract: BACKGROUND
  Hepatitis B vaccine is effective in infants. Preterm infants also respond but information on long term immunogenicity is limited.
  
  
  OBJECTIVE
  To compare response of premature and full term infants to hepatitis B vaccine.
  
  
  METHODS
  Sixty-nine prematurely born Alaska Native infants received three doses of hepatitis B vaccine beginning at discharge. Thirty-seven infants had paired serum samples drawn at approximately 1 and 3 years of life which were tested for antibody to hepatitis B surface antigen. One hundred eight infants born at full term enrolled in a separate study were used for comparison.
  
  
  RESULTS
  Both early and late blood sample antibody to hepatitis B surface antigen titers were lower in preterm than in term infants (23.1 mIU/ml vs. 56.8 mIU/ml, early blood sample; and 0.7 mIU/ml vs. 1.32 mIU/ml, late blood sample); however, these values were not statistically different. The drop in titer over time, however, was significant in both groups as was the decrease in the percent of infants with titers > or = 10 mIU/ml (preterm infants 75.7% early specimen and 8.1% late specimen compared with term infants 87% early specimen and 15% late specimen). Both prematurity and longer interval between third vaccination and blood sample were associated with a decreased antibody titer. No infant had evidence of hepatitis B viral infection by developing antibody to hepatitis B core antigen.
  
  
  CONCLUSIONS
  Preterm and term infants have a similar decline in antibody titers during the first 3 years, but preterm infants generally have a lower titer. The immunogenicity of the vaccine beyond 3 years and the need for revaccination in these populations requires further study.
authors.affiliation: Providence Alaska Medical Center, Anchorage 99508, USA. akneo@alaska.net
authors.forename: K
authors.initials: K
authors.lastname: Kesler
authors.forename: J
authors.initials: J
authors.lastname: Nasenbeny
authors.forename: R
authors.initials: R
authors.lastname: Wainwright
authors.forename: B
authors.initials: B
authors.lastname: McMahon
authors.forename: L
authors.initials: L
authors.lastname: Bulkow
mesh_terms: D002675:Child, Preschool; D005260:Female; D006510:Hepatitis B Antibodies / Q000096:biosynthesis*; D006514:Hepatitis B Surface Antigens / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000276:immunology*; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D004930:Inuit; D008297:Male; D014611:Vaccination
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines