SAFETY AND IMMUNOGENICITY OF A COMBINED DIPHTHERIA, TETANUS, PERTUSSIS AND HAEMOPHILUS-INFLUENZAE TYPE-B VACCINE IN YOUNG INFANTS

Objective. To study the safety and immunogenicity of a combined diphth eria-tetanus-pertussis (DTP)-Haemophilus influenzae type b (HbOC) vacc ine (TETRAMUNE) in infants as young as 2 months of age as compared to separate administration of DTP and HbOC. Methods. Two-month-old infant s were randomized to receive three doses 2 months apart of either DTP- HbOC as a single 0.5-mL injection or to receive 0.5 mL of DTP and HbOC concurrently in separate legs. Local and systemic adverse reactions w ere monitored within 72 hours of each immunization, and immunogenicity of each of the four vaccine components was measured. Results. The inc idence of both local and systemic adverse events following the tetrava lent vaccine was similar to the incidence following separate vaccine a dministration. After three doses of vaccine, the response to each of t he vaccine components was higher in the combined vaccine when compared to separate administration. In the case of the Haemophilus influenzae type b component, this enhancement was also seen after two doses. The response to the combined vaccine was consistent among the three lots tested as was the enhancement over separate administration. Conclusion s. The DTP-HbOC vaccine was safe and immunogenic in young infants and was generally more immunogenic than separate vaccination with DTP and HbOC. The use of such a combined vaccine reduces the number of injecti ons given to young infants by half and is an important step toward imp roving vaccine delivery.