Hepatitis B vaccination: long-term follow-up of the immune response of preterm infants and comparison of two vaccination protocols.
BACKGROUND
We conducted a 3-year follow-up study of long-term antibody persistence following vaccination of low-risk preterm infants with recombinant hepatitis B vaccine (HBV). Two three-dose protocols were compared: vaccination beginning within 24 h of birth to initial vaccination delayed until a weight of 2,000 g was reached.


METHODS
The study population included 136 children, divided into three groups: children born prematurely (< or = 35 weeks, n = 57), children born at term (> or = 37 weeks, n = 39), both groups receiving the first dose of HBV within 24 h of birth, and children born prematurely (< or = 35 weeks, n = 40), who received the first dose of HBV when a weight of 2,000 g was reached. All infants received the second hepatitis vaccination 1 month after the first, and the third dose 6 months after the first. Hepatitis B surface antibody (AntiHBs) was measured at an age of 3-3.5 years (at least 2.5 years after completion of the three-dose HBV series). An AntiHBs level of > or = 10 IU/l was considered positive.


RESULTS
At 3-3.5 years of age, a higher percentage of the premature-delayed vaccination group had a positive AntiHBs level (92.5%) compared to both the premature (54.4%, p < 0.001) and full-term groups (71.8%, p < 0.05) vaccinated soon after birth. The premature-delayed vaccination group also had a significantly higher geometric mean concentration (GMC) (119 vs 14.2 IU/l, p < 0.001 and 119 vs 32.7 IU/l, p < 0.005, respectively).


CONCLUSIONS
Delaying vaccination of premature infants against hepatitis B until a weight of 2,000 g was reached resulted in both a significantly higher percentage of children with positive antibody levels and a significantly higher GMC at 3-3.5 years of age as compared to early-vaccinated preterm and full-term infants. The known short-term advantage of delayed vaccination of preterm infants was shown to persist for at least the first 3 years of life.
Dept. of Neonatology, Schneider Children's Medical Center of Israel, Petah Tiqva. linderm@netvision.net.il
N
N
Linder
T H
TH
Vishne
E
E
Levin
R
R
Handsher
I
I
Fink-Kremer
D
D
Waldman
A
A
Levine
S
S
Ashkenazi
L
L
Sirota
D000367:Age Factors; D002675:Child, Preschool; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006509:Hepatitis B / Q000276:immunology* / Q000517:prevention & control*; D006514:Hepatitis B Surface Antigens / Q000032:analysis* / Q000097:blood; D017325:Hepatitis B Vaccines / Q000008:administration & dosage*; D006801:Humans; D007109:Immunity / Q000502:physiology; D007115:Immunization Schedule; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D007557:Israel; D008297:Male; D011336:Probability; D012680:Sensitivity and Specificity; D013997:Time Factors; D014611:Vaccination / Q000592:standards
D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines