Pertussis vaccination in infancy and asthma or allergy in later childhood: birth cohort study

Participants were the 13971 children who survived to 1 year in the Avon longitudinal study of parents and children.The children were categorised with regard to pertussis as fully vaccinated (DTP), partially vaccinated (DT but no pertussis)or non-vaccinated. Unajusted analyses showed significant association between doctor diagnosed asthma at 7 and a half year and vaccinations (P = 0.005). The significant associations disappeared after adjusting for confounding factors. The list of variables selected as potential confounders is impressive: maternal education, maternal smoking during pregnancy, maternal history of asthma and eczema, maternal financial difficulties, damp housing, overcrowding, child's ethnicity, number of siblings, contact with cats, duration of breastfeeding, passive exposure to tobacco smoke, birth weight, sex, gestational age and maternal age at delivery.