Response to hepatitis B vaccine in preterm babies.

INTRODUCTION: A well-accepted vaccination schedule for preterm babies is not available. We therefore studied the response to hepatitis B vaccine in preterm babies. METHODS: 60 babies born to HBsAg-negative mothers were studied. Group I (n=20) consisted of term babies with birth weight >2.5 Kg, group II (n=20) included preterm babies with birth weight between 1.8 and 2.49 Kg, and group III (n=20) included preterm babies with birth weight between 1.2 and 1.79 Kg. Mean gestational age in the three groups was 38.5 (1.1), 33.5 (1.4) and 32.7 (2.1) weeks, respectively. All babies received 3 doses (10 microg/0.5 mL) of a recombinant HBV vaccine within 3 days of birth, and at 6 weeks and 6 months of life. Anti-HBs levels were measured one month after the 2nd and 3rd doses each; the immune response was categorized as good responders (anti-HBs >100 mIU/mL, low responders (anti-HBs 10-100 mIU/mL) and non-responders (anti-HBs <10 mIU/mL). RESULTS: Good antibody response after the second dose was seen in 95% of babies in group I, 60% of those in group II and 10% of those in group III. This increased to 100%, 90% and 45%, respectively after the third dose. The response was influenced by gestational age (r=0.73); 94% of babies with gestational age 34-36 weeks attained good antibody response compared to only 55% of babies with gestational age of 31-33 weeks. Birth weight had no independent influence on the antibody response. CONCLUSION: The response to hepatitis B vaccine is influenced by gestational age. Hence, in preterm babies, it is advisable to check antibody titers one month after the third dose to assess the need for a booster dose.