title: Apnea after immunization of preterm infants.
abstract: OBJECTIVE
  To determine the frequency of adverse reactions, particularly the occurrence of apnea, among preterm infants after immunization with diphtheria and tetanus toxoids and whole cell pertussis vaccine adsorbed (DTP) and Haemophilus influenzae type b conjugate (HibC) vaccine in the neonatal intensive care unit.
  
  
  METHODS
  After the occurrence of apnea in two preterm infants following immunization with DTP and HibC, a prospective surveillance of 97 preterm infants younger than 37 weeks of gestation who were immunized with DTP (94 also received HibC at the same time) in the neonatal intensive care unit was performed to assess the frequency of adverse reactions and in particular, the occurrence of apnea. For each infant, data were recorded for a 3-day period before and after receipt of the immunization.
  
  
  RESULTS
  The majority of preterm infants tolerated immunizations with DTP and HibC without ill effects. However, 12 (12%) infants experienced a recurrence of apnea, and 11 (11%) had at least a 50% increase in the number of apneic and bradycardic episodes in the 72 hours after immunization. This occurred primarily among smaller preterm infants who were immunized at a lower weight (p = 0.01), had experienced more severe apnea of prematurity (p = 0.01), and had chronic lung disease (p = 0.03).
  
  
  CONCLUSIONS
  The temporal association observed between immunization of preterm infants and a transient increase or recurrence of apnea after vaccination merits further study. Cardiorespiratory monitoring of these infants after immunization may be advisable.
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Sánchez
authors.forename: A R
authors.initials: AR
authors.lastname: Laptook
authors.forename: L
authors.initials: L
authors.lastname: Fisher
authors.forename: J
authors.initials: J
authors.lastname: Sumner
authors.forename: R C
authors.initials: RC
authors.lastname: Risser
authors.forename: J M
authors.initials: JM
authors.lastname: Perlman
mesh_terms: D001049:Apnea / Q000139:chemically induced*; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000009:adverse effects*; D005260:Female; D005865:Gestational Age; D018073:Haemophilus Vaccines / Q000009:adverse effects*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D008297:Male; D011446:Prospective Studies; D012008:Recurrence
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines