Fig. 2

Mean (95% confidence intervals) diphtheria, tetanus and pertussis antibody titres by season of infant first DTP vaccination. The bar charts compare the means diphtheria, tetanus and pertussis antibody titres at 12 weeks (A, B and C, respectively) and 24 weeks (D, E and F, respectively) by season of first DTP vaccination in infants. In The Gambia, the dry/harvest season lasts from November to May and the rainy/hungry season from June to October. Mean antibody titres measured at 12 weeks, following the first DTP vaccination, were adjusted with maternal variables: age, BMI and formal education (yes/no) at enrolment, Hb levels at 30 weeks gestation, weight gain from enrolment to 30 weeks gestation, morbidity, supplement group and compliance to supplementation from enrolment to delivery; and with infant variables: GA at delivery, sex, WLZ at first vaccination, Hb levels at 12 weeks, morbidity, EBF (yes/no), and Fourier terms of month of mid-gestation or first vaccination. Mean antibody titres measured at 24 weeks, following the third DTP vaccination, were adjusted with the same factors mentioned above, with changes for infant WLZ at third vaccination, Hb levels at 24 weeks and morbidity and EBF (yes/no) from birth to 24 weeks