Hepatitis B vaccination in preterm infants

Preterm infants, especially those with very low birth weight, are at risk o f hepatitis B virus infection. They often require invasive diagnostic metho ds in their first weeks of life, intensive treatment and long-term hospital isation. Therefore, hepatitis B vaccination is particularly justified in th ese patients. Our aim was to determine the reaction of preterm children to hepatitis B vaccination. The study comprised 64 preterm children whose birt h weight ranged from 700 g to 2460 g (mean 1776.6 g +/- 480.4 g) and whose gestational age was between 25 and 36 weeks. A 10 mu g dose of the recombin ant vaccine Engerix-B (SmithKline Beecham) was given at intervals of 0, 1, 2 and 12 months. In 49.2% of the children vaccination was administered on t he Ist day of life, and in the remaining cases between the 2nd and 119th da ys post delivery. One month after vaccination completion the levels of anti -hepatitis B surface antigen (HBs) antibodies were evaluated. In 98.4% of t he vaccinated preterm infants the level of antibodies was >10 mIU/ml. Mean level of anti-HBs antibodies in the group of children with birth weight les s than or equal to 2000 g was 2431.4 mIU/ml, while in those with birth weig ht: >2000 g it was 4803.9 mIU/ml. In children with a birth weight less than or equal to 1000 g, the mean level of anti-HBs antibodies was significantl y lower than in those with birth weight >2000 g. The level of anti-HBs anti bodies in children who started vaccination >1st day of life was significant ly lower in preterm children with a birth weight less than or equal to 2000 g than in those with a birth weight >2000 g. Although vaccination was started on the 1st day of his life, one child with birth weight of 2300 g developed a hepatitis B virus infection. One child did not respond to vaccination (anti-HBs < 10 mIU/ml) and in three cases th e response was very poor (11-100 mIU/ml). These patients were given a suppl ementary booster double dose of Engerix B (20 mu g). After 1 month the leve l of anti-HBs antibodies was evaluated again and high values of 657 mIU/ml to 14520 mIU/ml were observed. In the group of children with a birth weight less than or equal to 1000 g t he response to vaccination was weaker as compared to children with a birth weight >2000 g (P < 0.05). In systematic mass vaccination programmes, monit oring of antibody levels is not recommended unless the patient is at risk. However, in extremely preterm infants (< 1000 g at birth), especially after very serious infections, monitoring the level of anti-HBs antibodies after complete immunisation should be considered. In preterm infants who show ve ry low postvaccination levels of anti-HBs antibodies, stimulation with an a dditional double booster dose of vaccine gives positive results. Conclusion: The majority of preterm infants (98.4%) responded well to hepat itis B vaccination given at intervals of 0, 1, 2 and 12 months and develope d a protective level of antibodies. The level of anti-hepatitis B surface a ntigen antibodies in children with a birth weight >2000 g was higher than i n those with a birth weight less than or equal to 1000 g.