A randomized controlled trial of the effect of pertussis vaccines on atopic disease.

BACKGROUND Pertussis vaccination in infancy has been suggested to increase the risk for development of asthma and allergy. OBJECTIVE To assess sensitization rates and development of atopic diseases in a prospective randomized controlled trial of pertussis vaccine. PATIENTS AND METHODS A total of 669 children were randomized to 1 of 4 vaccine groups (2-component acellular pertussis, 5-component acellular pertussis, whole-cell pertussis vaccines, and placebo [diphtheria and tetanus toxoids]). Diphtheria and tetanus toxoids were also given to the children in the pertussis vaccine groups. The children were evaluated by means of questionnaires at age 2 months, 7 months, and 2 1/2 years; skin prick tests at age 7 months and 2 1/2 years; and blinded clinical investigation at age 2 1/2 years. The families were contacted at regular intervals to assess possible adverse effects after the vaccinations and symptoms of whooping cough. RESULTS The cumulative incidence of atopic diseases was 30% and incidence rates were similar in the 4 groups after adjusting for family history. Exposure to environmental tobacco smoke and home dampness did not confound these results. The frequency of adverse effects did not differ appreciably between atopic and nonatopic children, with the exception that a nodule at the vaccination site was more frequent after whole-cell pertussis vaccination in the nonatopic children. Among 47 children with proven pertussis, atopic disease appeared in 19 (40%). Of these 47 children, 9 (19%) developed asthma, as compared with 58 (9%) noninfected children (P=.03). CONCLUSIONS We found no support for a drastic increase in allergic manifestations after pertussis vaccination. There was a positive association between whooping cough and asthma by 2 1/2 years of age. There seems to be little reason to withhold pertussis vaccination from infants, irrespective of family history of allergy.