title: Response of 7- to 15-month-old infants to sequential immunization with Haemophilus influenzae type b-CRM197 conjugate and polysaccharide vaccines.
abstract: OBJECTIVE
  To evaluate the immunologic potential of infants 7 to 15 months of age to respond to Haemophilus influenzae type b polysaccharide vaccine following immunization with H influenzae b oligosaccharide-CRM197 conjugate vaccine.
  
  
  METHODS
  One hundred seventy-one infants, aged 7 to 15 months, were consecutively and alternatively assigned to one of three immunization protocols. Group 1 (n = 71) received three doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine, group 2 (n = 47) received two doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine followed by one dose of H influenzae type b polysaccharide vaccine, and group 3 received one dose of H influenzae b oligosaccharide-CRM197 conjugate vaccine followed by two doses of H influenzae type b polysaccharide vaccine. Immunizations were given on day 0 and at 2 months and 6 months. Anti-H influenzae type b polysaccharide antibody levels were measured on day 0 and 2, 3, 6, 7, and 12 months after the study began.
  
  
  RESULTS
  Haemophilus influenzae type b polysaccharide vaccine given as a second dose stimulated an antibody rise but did so less effectively than H influenzae b oligosaccharide-CRM197 conjugate vaccine. Two doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine were highly immunogenic; geometric means were 31 and 35 micrograms/mL in the 7- to 11-month and 12- to 15-month age groups, respectively. Following two doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine, both immunization protocols resulted in (1) equally high geometric mean antibody levels 1 month after immunization and (2) similar geometric mean antibody levels 6 months after immunization.
  
  
  CONCLUSIONS
  Haemophilus influenzae b oligosaccharide-CRM197 conjugate vaccine induces antibody levels that would be expected to protect infants from initial invasion and primes the immune system for an anamnestic response. Our data indicate that if a booster immunization is needed, H influenzae type b polysaccharide vaccine could be an alternative to H influenzae b oligosaccharide-CRM197 conjugate vaccine.
authors.affiliation: Pennridge Pediatrics Associates, Sellersville, PA.
authors.forename: E P
authors.initials: EP
authors.lastname: Rothstein
authors.forename: R P
authors.initials: RP
authors.lastname: Schiller
authors.forename: J A
authors.initials: JA
authors.lastname: Girone
authors.forename: T J
authors.initials: TJ
authors.lastname: Hipp
authors.forename: R L
authors.initials: RL
authors.lastname: Souder
authors.forename: H H
authors.initials: HH
authors.lastname: Bernstein
authors.forename: D V
authors.initials: DV
authors.lastname: Madore
authors.forename: C L
authors.initials: CL
authors.lastname: Johnson
authors.forename: D H
authors.initials: DH
authors.lastname: Smith
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis; D000917:Antibody Formation; D016667:Bacterial Capsules; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007156:Immunologic Memory; D007223:Infant; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000276:immunology*; D013997:Time Factors; D014611:Vaccination; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D011135:Polysaccharides, Bacterial; D014614:Vaccines, Synthetic; C061963:HibTITER protein, Haemophilus influenzae