New research suggests that babies treated with antibiotics in their first few weeks of life have reduced immune responses to vaccines in later infancy, likely due to changes in the gut microbiome. The Australian study tracked 191 healthy babies from birth, finding that those who received antibiotics in the newborn period had significantly lower levels of antibodies against multiple vaccines at seven and 15 months. The study, published in the journal Nature, assessed the infants' microbiomes around the time of their first routine vaccinations at six weeks, finding that babies directly treated with antibiotics at birth had less of a group of beneficial gut bacteria known as Bifidobacterium. The reduction in Bifidobacterium was linked to lower antibody levels against multiple components of the pneumococcal vaccine, as well as Haemophilus influenzae type b, at both seven and 15 months.
