Immune responses of prematurely born infants to hepatitis B vaccination: results through three years of age.
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.
Kesler
K
K
Providence Alaska Medical Center, Anchorage 99508, USA. akneo@alaska.net
Nasenbeny
J
J
Wainwright
R
R
McMahon
B
B
Bulkow
L
L
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
D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines