Immunogenicity and reactogenicity of a combined adsorbed tetanus toxoid, low dose diphtheria toxoid, five component acellular pertussis and inactivated polio vaccine in six-year-old children.

BACKGROUND: The objective of this study was to assess the immunogenicity and reactogenicity of the combined adsorbed tetanus toxoid, low dose diphtheria toxoid, 5-component acellular pertussis and inactivated polio vaccine (TdcP-IPV) as compared with a pediatric dose diphtheria formulation, combined with adsorbed tetanus toxoid and 3-component acellular pertussis (DTacP), in 6-year-old children who were immunized with 4 doses of diphtheria-tetanus-whole cell cellular pertussis (DTwcP) plus oral polio vaccine (OPV) before 2 years of age, according to the local Spanish vaccination calendar. METHODS: One hundred ninety-four healthy 6-year-old children were randomized to receive 1 dose of TdcP-IPV or 1 dose of DTacP and OPV. RESULTS: One month postvaccination, antidiphtheria and antitetanus titers were > or =0.1 IU/mL in 100% of patients in both study groups. TdcP-IPV reached 100% seroprotection rates against polio types 1, 2 and 3. In OPV recipients, these rates were 100, 100 and 96.8%, respectively. Seropositivity rates for pertussis toxin, filamentous hemagglutinin, pertactin and fimbrial components of the TdcP-IPV vaccine were 97.9, 89.6, 90.6 and 100%. The incidence of local and systemic reactions was 50.5 and 39.2% in the TdcP-IPV group and 59.4 and 38.5% in the DTacP plus OPV group, and no serious adverse events were reported. CONCLUSIONS: TdcP-IPV vaccine was shown to be immunogenic and safe when given as a booster in children 6 years of age who were primed with 4 doses of DTwcP and OPV.