PRIMING WITH DIPHTHERIA-TETANUS-PERTUSSIS VACCINE ENHANCES THE RESPONSE TO THE HAEMOPHILUS-INFLUENZAE TYPE-B TETANUS CONJUGATE VACCINE IN INFANCY

Haemophilus influenzae type b (Hib) capsular polysaccharide (PS) conju gated to tetanus toroid (PRP-T) was given at 4 and 6 months of age and anti-Hib PS antibody response to the first and second dose of PRP-T w as compared in groups that received diphtheria-tetanus-pertussis (DTP) vaccine either simultaneously with PRP-T (34 infants) or separately a t 3, 4 and 5 months of age (49 infants). The geometric mean anti-Hib P S antibody concentration after the first dose of PRP-T given at 4 mont hs of age was eightfold higher if the infants primed with DTP at 3 mon ths of age than if the first dose of DTP was given together with the f irst dose of PRP-T (0.81 mu g ml(-1) vs 0.11 mu g ml(-1)). The positiv e influence of DTP priming was seen also after the second dose of PRP- T given at 6 months of age (7.55 mu g ml(-1) vs 3.45 mu g ml(-1)). Cop yright (C) 1996 Elsevier Science Ltd.