EFFECT OF COMBINATION WITH AN ACELLULAR PERTUSSIS, DIPHTHERIA, TETANUS VACCINE ON ANTIBODY-RESPONSE TO HIB VACCINE (PRP-T)

Acellular pertussis vaccines provide protection against whooping cough with few adverse effects, Their introduction to routine immunisation programmes would be facilitated by their incorporation with other rout inely administered vaccines. 262 infants were immunised with an acellu lar pertussis vaccine containing pertussis toxin and filamentous haema gglutinin, combined with diphtheria and tetanus toxoids. This vaccine was mixed with Haemophilus influenzae type b tetanus toxoid vaccine (P RP-T) so that infants received a single injection at age 2, 3 and 4 mo nths. One month after the third dose the geometric mean titre of Hib I gG antibody was 0.48 mu g ml(-1). Eighty-two percent of infants achiev ed a titre of 0.15 mu g ml(-1), with only 27% achieving 1.0 mu g ml(-1 ) This combination vaccine induced low Hib antibody responses when com pared to other studies in which PRP-T was mixed with acellular or whol e-cell pertussis vaccines. The combined vaccine did, however, appear t o prime a subset of 35 infants for response to a fourth dose of PRP-T at 13 months of age, with a rise in GMT from 0.21 mu g ml(-1) to 36.8 mu g ml(-1). These data have important implications for the introducti on of combination acellular pertussis vaccines. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.