title: Effect of priming with diphtheria and tetanus toxoids combined with whole-cell pertussis vaccine or with acellular pertussis vaccine on the safety and immunogenicity of a booster dose of an acellular pertussis vaccine containing a genetically inactivated pertussis toxin in fifteen- to twenty-one-month-old children. Italian Multicenter Group for the Study of Recombinant Acellular Pertussis Vaccine.
abstract: OBJECTIVE
  To evaluate the safety and the immunogenicity of a booster dose of recombinant acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTaP, Biocine SpA) in 15- to 21-month-old children primed in infancy with either whole-cell diphtheria-tetanus-pertussis (DTwP) vaccine or DTaP vaccine.
  
  
  METHODS
  Open-label second phase of a double-masked, controlled trail, with masked analysis of serum samples.
  
  
  METHODS
  Three hundred fifty children, 15 to 21 months of age, who had been primed at 2, 4, and 6 months of age with either three doses of DTaP vaccine (n = 173) or DTwP vaccine (n = 177). The children were enrolled in eight vaccination centers in Italy.
  
  
  METHODS
  All children received a booster dose of the DTaP vaccine and were examined for safety at 48 hours and at 7 days after vaccination. Serum samples for evaluation of immunogenicity were obtained from 196 (55%) of the 350 children.
  
  
  METHODS
  IgG antibodies to pertussis toxin (Ptox), filamentous hemagglutinin, 69-kilodalton protein, and tetanus toxoid were measured by enzyme-linked immunosorbent assay. Pertussis toxin-neutralizing antibodies were measured by the Chinese hamster ovary cell toxin neutralization assay.
  
  
  RESULTS
  Adverse reactions to DTaP were infrequent, and there was no difference in the incidence of local or systemic reactions in children given DTaP as a fourth dose in comparison with a first dose. One month after the DTaP booster vaccination, both groups had 6- to 40-fold increases in serum antibody concentrations to all antigens tested; the concentrations against the three pertussis antigens were higher in the DTaP-primed children (p < 0.05). The antibody titers to diphtheria and tetanus toxoids were higher in the DTwP-primed group (p < 0.05), but both groups had protective titers. The geometric mean ratio of anti-Ptox neutralizing antibody per unit of IgG anti-Ptox antibody was higher in the DTaP-primed group (p < 0.001).
  
  
  CONCLUSIONS
  There are quantitative and qualitative differences in booster responses to DTaP vaccine in young children, depending on whether they were given DTaP or DTwP as primary immunization. This DTaP vaccine is safe and highly immunogenic as a booster.
authors.affiliation: Biocine SpA, Siena, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Podda
authors.forename: G
authors.initials: G
authors.lastname: Bona
authors.forename: G
authors.initials: G
authors.lastname: Canciani
authors.forename: A M
authors.initials: AM
authors.lastname: Pistilli
authors.forename: B
authors.initials: B
authors.lastname: Contu
authors.forename: R
authors.initials: R
authors.lastname: Furlan
authors.forename: T
authors.initials: T
authors.lastname: Meloni
authors.forename: D
authors.initials: D
authors.lastname: Stramare
authors.forename: L
authors.initials: L
authors.lastname: Titone
authors.forename: R
authors.initials: R
authors.lastname: Rappuoli
mesh_terms: D000907:Antibodies, Bacterial / Q000096:biosynthesis; D001886:Bordetella pertussis / Q000276:immunology*; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000009:adverse effects / Q000276:immunology; D004311:Double-Blind Method; D004797:Enzyme-Linked Immunosorbent Assay; D005500:Follow-Up Studies; D006801:Humans; D007117:Immunization, Secondary; D007223:Infant; D037342:Pertussis Toxin; D010567:Pertussis Vaccine / Q000009:adverse effects / Q000276:immunology; D013997:Time Factors; D014614:Vaccines, Synthetic / Q000009:adverse effects / Q000276:immunology; D010566:Virulence Factors, Bordetella; D014917:Whooping Cough / Q000517:prevention & control*
chemical_list: D000907:Antibodies, Bacterial; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D010567:Pertussis Vaccine; D014614:Vaccines, Synthetic; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin