title: Antipolyribosyl ribitol phosphate response of premature infants to primary and booster vaccination with a combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio virus/Haemophilus influenzae type b vaccine.
abstract: BACKGROUND
  Prematurity may be a risk factor for Haemophilus influenzae type b vaccine failure. This article evaluates the Haemophilus influenzae type b immunogenicity of a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b vaccine in preterm infants (< 37 weeks' gestation).
  
  
  METHODS
  This was an open-label, parallel group study. Preterm (N = 94) and term infants (N = 92) received 3 doses of a diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b vaccine at 2, 4, and 6 months with a booster dose at 18 to 20 months. Antipolyribosyl ribitol phosphate antibody concentrations were determined in serum samples taken before and 1 month after primary and booster vaccination.
  
  
  RESULTS
  Postprimary seroprotection rates (antipolyribosyl ribitol phosphate > or = 0.15 microg/mL) were lower in preterm than in term infants (92.5% vs 97.8%), with antipolyribosyl ribitol phosphate geometric mean concentrations of 2.241 vs 4.247 microg/mL. A progressive reduction in immune response to the Haemophilus influenzae type b antigen was observed with decreasing length of gestation and decreasing birth weight when cutoff > or = 1 microg/mL was considered. Prebooster seroprotection rates and antipolyribosyl ribitol phosphate geometric mean concentrations were low in both groups (antipolyribosyl ribitol phosphate > or = 1.0 microg/mL in 10.7% of preterm and 28.4% of term infants). A vigorous response to booster vaccination was seen in both groups, with no differences in postbooster seroprotection rates or antipolyribosyl ribitol phosphate geometric mean concentrations between the 2 groups (antipolyribosyl ribitol phosphate > or = 1.0 microg/mL in 100% of preterm and 98.5% of term infants).
  
  
  CONCLUSIONS
  Primary vaccination with a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b vaccine at 2, 4, and 6 months with a booster dose at 18 to 20 months elicits a satisfactory antipolyribosyl ribitol phosphate response in preterm infants compared with term controls. Immunologic response decreased with decreased gestational age and birth weight.
authors.affiliation: Department of Neonatology, La Paz Hospital, Madrid, Spain.
authors.forename: Felix
authors.initials: F
authors.lastname: Omeñaca
authors.forename: José
authors.initials: J
authors.lastname: Garcia-Sicilia
authors.forename: Pilar
authors.initials: P
authors.lastname: García-Corbeira
authors.forename: Reyes
authors.initials: R
authors.lastname: Boceta
authors.forename: Victorio
authors.initials: V
authors.lastname: Torres
mesh_terms: D000917:Antibody Formation; D016667:Bacterial Capsules; D001724:Birth Weight; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D005865:Gestational Age; D018073:Haemophilus Vaccines / Q000276:immunology; D017325:Hepatitis B Vaccines; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology*; D011054:Poliovirus Vaccine, Inactivated; D011134:Polysaccharides / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D017778:Vaccines, Combined / Q000276:immunology*
chemical_list: C451839:DTPa-HBV-IPV combined vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D017325:Hepatitis B Vaccines; D011054:Poliovirus Vaccine, Inactivated; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; D017778:Vaccines, Combined; C008984:polyribitol phosphate