Immune response to tetanus booster in infants aged 15 months born prematurely with very low birth weight

► Preterm infants had lower antibody levels before tetanus booster at 15 months. ► Breastfeeding was associated with higher tetanus antibody levels before booster dose. ► Lower antibody levels were found in infants born before 32 weeks of gestation. ► Preterm and full term infants had similar immune response after tetanus booster dose.