Evaluation of the pertussis components of diphtheria-tetanus-pertussis vaccine.

The adjuvant and antigen components of the pertussis fraction of diphtheria-tetanus-pertussis (DTP) vaccine were evaluated. Four preparations of DTP vaccine composed of either whole cell (Wc) or extracted (E) pertussis antigen combined with either an aluminum phosphate (Ph) or alum (Al) adjuvant were compared. Local reactions were similar in all four vaccines after the first two immunizations but were significantly increased in incidence and severity following the third immunization with vaccine WcPh. This appeared to be due to the Ph adjuvant rather than the antigen component. Febrile reactions were experienced more often (P = .0009) and with higher temperatures (P = .0001) with the WcPh vaccine following the first immunization. This appeared to be due to the Wc component. Comparing the pooled Wc groups with the pooled E groups revealed a greater febrile response in the Wc group after both the first (P = .0008) and the second (P = .03) immunization. Local reactions appear temporally and etiologically to be distinct from febrile reactions. The pooled Wc antigen group produced a higher geometric mean titer than the pooled E antigen group (P = .05). Serologic responses, with respect to geometric mean titer, were not significantly different among the individual vaccines. This study suggests that the combination of whole cell and aluminum phosphate, which is currently in use in the United States, is probably not the optimal formulation for pertussis vaccine.