Immunogenicity and reactogenicity of acellular diphtheria/tetanus/pertussis vaccines given as a pre-school booster: effect of simultaneous administration of MMR

Four acellular diphtheria/tetanus/pertussis (aDTP) vaccines were compared w ith two diphtheria/tetanus (DT) vaccines given as a pre-school booster to 1 033 children aged 4 to < 6 years who had completed primary immunisation wit h DTP vaccine according to the UK 2, 3 and 4 month schedule; 71 children ha d received aDTP vaccine and the remaining 962 a whole cell DTP vaccine for primary immunisation. The effect of simultanous administration of a second dose of MMR vaccine was evaluated in 374 (37%). Overall, there was little d ifference in the frequency of post-vaccination symptoms in DT and aDTP vacc inees, although local reactions occurred more quickly in the aDTP group. Th e concomitant administration of MMR had no effect on local reactions or fev er within 10 days, or on the proportions requiring a doctor's visit in the 4-6 week post-vaccination period. Local reactions 2 3 cm were higher on day 2 in children who had received aDTP for primary immunisation (erythema 32. 4% vs. 17.4% for wDTP, P = 0.0012; swelling 28.2% vs. 15.5%, P = 0.0027). P ertussis antibody responses were consistent with the antigen content of the aDTP vaccines. All were more immunogenic with respect to PT - the only per tussis antigen which by itself has been shown to be protective in clinical trials - than a wDTP pre-school booster given in an earlier trial. MMR vacc ine had no significant effect on antibody responses to either the pertussis or diphtheria and tetanus antigens. Diphtheria antibody responses in child ren who had received wDTP for-primary immunisation were 2.8 times higher th an in those who had received aDTP vaccine (P < 0.0001); they were also high er in children who had received a single dose of a Haemophilus influenzae t ype b vaccine containing CRM197 conjugate after 12 months of age. For count ries currently using DT vaccines as a pre-school booster, replacement with an aDTP vaccine is unlikely to have a perceptable effect on reactogenicity, at least in children given wDTP for primary immunisation, and would boost antibody levels to antigens known to be associated with protection. (C) 200 1 Elsevier Science Ltd. All rights reserved.