Antibody titre against 3 doses of hepatitis B vaccine among preterm and term babies.

This cross sectional study was conducted to assess seroprotection by completed 3 doses of hepatitis B vaccine in routine EPI schedule in preterm & LBW as well as term appropriate weight babies and to compare the immune response among them. The study was conducted in EPI centre of Dhaka Medical College Hospital where 50 preterm (<37 completed weeks of gestation) and low birth weight (<2500 gm) infants enrolled in group A and 50 term (37-42 completed weeks of gestation) appropriate weight (≥2500 gm) in group B. All infants were immunized with 3 doses of hepatitis B vaccine according to EPI schedule and first vaccine was given at 6 weeks after birth and subsequent doses are given at one month interval. Adverse events were monitored. Anti HBs titre was determined 1 month after 3rd dose of vaccine from serum by ELISA method (VITROS anti HBs reagent pack). Seroprotectivity (anti HBs titres >10 mIU/ml) of hepatitis B vaccine after 3 doses were 94% and 98% in group A and B respectively (p>0.05). However, the preterm infants had a lower geometric mean titre of antibodies after 3 doses of vaccine than did the term infants (92.75 mIU/ml vs. 310.59 mIU/ml respectively; p<0.001). After 3 doses of hepatitis B vaccine though the seroprotective anti HBs titre (i.e. >10 mIU/ml) was ~96% irrespective of gestational age and birth weight but good antibody titre (i.e. >100 mIU/ml) was found among preterm babies having gestational age >34 weeks (73.6%) and birth weight >2000 gm (64%).