On birth single dose live attenuated OPV and BCG vaccination induces gut cathelicidin LL37 responses at 6 week of age: a natural experiment.

In a cross sectional study, we show that infants who received single dose of live attenuated OPV and BCG vaccines within 48h of birth, have higher excretion of human cathelicidin LL37 (p<0.05) in stool at 6wk of age. This response remained unchanged in multivariate analysis after adjusting for sex, mode of delivery, infant age, mother age birth weight and breast milk feeding pattern. This analysis also reveals that irrespective of vaccination, girl infants have higher human-beta-defencin2 (HBD2) and exclusively breastfed infants have higher total and anti-polio specific IgA to all three subtypes in stool (p<0.05). However, vaccination induces anti-polio IgA responses only to infants who are exclusively breastfed. Thus on-birth live attenuated vaccination may provide non-specific beneficial effect against infections while exclusive breastfeeding enhance protection by boosting vaccine induced IgA. The result also suggests that in polio endemic area, exclusive breastfeeding may be sufficient for mucosal anti-polio responses during early infancy.