Immunogenicity and safety of a DTaP–IPV//PRP~T combination vaccine given with hepatitis B vaccine: a randomized open- label trial

Objective To determine seroprotection and vaccine response rates produced by a diphtheria–tetanus–acellular pertussis–inactivated poliovirus–Haemophilus influenzae type-b conjugate (DTaP–IPV//PRP~T) vaccine containing a polyribosyl-ribitol-phosphate (PRP)– tetanus toxoid conjugate (PentaximTM) and given with a hepatitis B vaccine. Methods In this multicentre open-label trial, 424 infants who received DTaP–IPV//PRP~T at 6, 10 and 14 weeks of age were also randomized to receive hepatitis B vaccine at either 6, 10 and 14 weeks or 0, 6 and 14 weeks of age. Antibody levels were determined at 6 and 18 weeks of age, and reactogenicity was monitored using parental reports. Findings Immunogenicity was high for all vaccine antigens and was similar to that in a historical control study. After primary vaccination, 98.7% of all infants had an anti-PRP antibody titre 3 0.15 μg/ml. Seroprotection against poliovirus type-1, -2 and -3 and tetanus was obtained in all infants, and against diphtheria, in 97.1%. Pertussis seroconversion, defined as a 3 fourfold increase in antibody titre, occurred in 95.3% for anti-pertussis toxoid antibody and in 89.0% for anti-filamentous haemagglutinin antibody. The hepatitis B seroprotection rate was 99.5% with administration at 0, 6 and 14 weeks, and 97.8%, at 6, 10 and 14 weeks. However, the antibody titre was higher with the 0, 6 and 14-week schedule (601 mIU/ml versus 207 mIU/ml). The reactogenicity of both vaccines was low. Conclusion The DTaP–IPV//PRP~T vaccine was highly immunogenic. The anti-hepatitis B antibody response was seroprotective with both schedules, though the antibody titre was higher with the 0, 6 and 14-week schedule.