title: Immunization levels among premature and low-birth-weight infants and risk factors for delayed up-to-date immunization status. Centers for Disease Control and Prevention Vaccine Safety Datalink Group.
abstract: BACKGROUND
  Studies have noted that health care professionals may not conform to proper immunization schedules for premature and low-birth-weight infants in the United States. Little is known about the success of current efforts to immunize these high-risk infants.
  
  
  OBJECTIVE
  To describe current immunization practices for premature and low-birth-weight infants and ascertain risk factors for poor immunization status, using large population-based data sources.
  
  
  METHODS
  Cohort and case-control analyses of immunization data tracked from March 1991 through March 1997 for 3 large health maintenance organizations (HMOs) participating in the Centers for Disease Control and Prevention's Vaccine Safety Datalink project.
  
  
  METHODS
  A total of 11580 low-birth-weight and premature infants were enrolled from birth to age 2 months; 6832 of these were continuously enrolled from birth to age 24 months. At age 2 months, there were 173373 full-term, normal-birth-weight infants enrolled as controls; at age 24 months, there were 103 324.
  
  
  METHODS
  Age-specific immunization status by prematurity and birth weight (<1500 g, 1500-2500 g, born at <38 weeks' gestation with birth weight of >2500 g, or full-term with normal birth weight) and patient characteristics associated with up-to-date status.
  
  
  RESULTS
  At each age, infants weighing less than 1500 g at birth had lower up-to-date immunization levels than other infants. At age 6 months, 52% to 65% of infants weighing less than 1500 g were up-to-date at each of the 3 HMOs compared with 69% to 73% of those weighing 1500 to 2500 g, 66% to 80% of premature infants weighing more than 2500 g, and 65% to 76% of full-term, normal-birth-weight infants. By age 24 months, 78% to 86% of infants weighing less than 1500 g were up-to-date, significantly less than heavier infants, who had levels of 84% to 89%. Well-child preventive care strongly predicted immunization status, while concomitant pulmonary disease did not.
  
  
  CONCLUSIONS
  Our data suggest that infants born prematurely are vaccinated at levels approaching that of the general population, but levels of vaccination for very low-birth-weight infants lag slightly behind.
authors.affiliation: Immunization Studies Program, Center for Health Studies, Group Health Cooperative of Puget Sound, Seattle, Wash, USA. rdavis@u.washington.edu
authors.forename: R L
authors.initials: RL
authors.lastname: Davis
authors.forename: D
authors.initials: D
authors.lastname: Rubanowice
authors.forename: H R
authors.initials: HR
authors.lastname: Shinefield
authors.forename: N
authors.initials: N
authors.lastname: Lewis
authors.forename: D
authors.initials: D
authors.lastname: Gu
authors.forename: S B
authors.initials: SB
authors.lastname: Black
authors.forename: F
authors.initials: F
authors.lastname: DeStefano
authors.forename: P
authors.initials: P
authors.lastname: Gargiullo
authors.forename: J P
authors.initials: JP
authors.lastname: Mullooly
authors.forename: R S
authors.initials: RS
authors.lastname: Thompson
authors.forename: R T
authors.initials: RT
authors.lastname: Chen
mesh_terms: D006279:Health Maintenance Organizations / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D007230:Infant, Low Birth Weight / Q000276:immunology; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology; D007235:Infant, Premature, Diseases / Q000276:immunology; D016015:Logistic Models; D008171:Lung Diseases / Q000276:immunology; D011159:Population Surveillance; D012307:Risk Factors; D014481:United States; D014611:Vaccination / Q000592:standards / Q000706:statistics & numerical data*