Underimmunization of very low birth weight infants at discharge from the neonatal intensive care unit

Objective To quantify immunization status among premature infants discharged from neonatal intensive care units (NICUs), and identify risk factors for underimmunization. Study design We performed a cohort study of infants <33 weeks gestation discharged home between 2011 and 2020 from 241 NICUs. Using multivariable logistic regression, we examined the association between risk factors and underimmunization at discharge, defined as <1 dose of 5 vaccine types when discharged at 60–119 days of age and <2 doses when discharged at 120–179 days of age. Results Of 30,766 infants discharged at 60–119 days of age, 14% were underimmunized. Among 4358 infants discharged at 120–179 days of age, 53% were underimmunized. For infants discharged at 60–119 days of age, ventilator support within 30 days of discharge was associated with underimmunization. Having a surgical procedure was associated with underimmunization in both groups. Conclusion A large proportion of premature infants discharged from the NICU are underimmunized.