234 toddlers were equally randomized to receive one dose of Takeda acellular pertussis vaccine combined with D and T either simultaneously with HbOC (DTaP + HbOC) or combined in the same syringe (DTaP/HbOC; TETRACEL™). Enrollment was stratified into 2 age groups: 12 to < 15 mo. and ≥ 15 mo. to 18 mo. IgG antibody to PRP, measured by standardized EIA methods on pre and 1 mo. post-vaccination bloods are shown below:Table

Table 1

Anti-PRP responses were comparable following combined and concurrent vaccination.

Post vaccination GMTs were higher among the older children, but the differences were not significant. DTaP/HbOC was highly immunogenic in both age groups.

We conclude that DTaP/HbOC is effective as a booster in children aged 12 - 18 mo.