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.