Safety and immunogenicity of Biken acellular pertussis vaccine in combination with diphtheria and tetanus toxoid as a fifth dose at four to six years of age

Objectives. To evaluate the safety and immunogenicity of Biken acellular pertussis vaccine in combination with diphtheria and tetanus toxoid (Biken DTaP) vaccine administered to children 4 to 6 years of age who had previously received four doses of Biken DTaP. Methods. 580 children were enrolled to receive one dose of Biken DTaP. Local and systemic reactions were collected by parent diary for all subjects within 3 days after vaccination and in a subset for 14 days. All adverse events occurring within 30 days after vaccination were recorded. Results. Any redness and swelling occurred in 59.8 and 61.4%, respectively. Redness or swelling larger than 5 cm/10 cm occurred in 31%/6.1% and 25%/6.5% of the children, respectively. Any pain was reported in 58.8%, but clinically significant pain occurred in 2.1% of the children. Fever > 38.0 degreesC occurred in 3.8% of the children. Fussiness, drowsiness, anorexia and vomiting were experienced by 19.7, 15.5, 7.3 and 2.2%, respectively. Sixty-three of 247 adverse events (25%) occurring within 30 days after vaccination were assessed to possibly be vaccine-related. Fifty-eight of the 63 possibly related events (92%) were caused by local reactions as redness, swelling or itchiness. The remaining 5 events included hematoma, headache, stomachache and sleep disturbance. All local and systemic reactions and adverse events resolved without sequelae. Immunogenicity analysis showed a 4-fold antibody increase to pertussis toxin in 97% of subjects and to filamentous hemagglutinin in 82%. All subjects had postvaccination antibody titers of 0.1 IU/ml or greater against diphtheria and tetanus. Higher prevaccination antibody titers against diphtheria toxoid, pertussis toxin and filamentous hemagglutinin were associated with a higher frequency of large local reactions. Conclusion. In comparison with a fourth dose of Biken DTaP administered at 18 to 24 months of age in the same population, the rate of local reactions increased after the fifth dose, whereas systemic reactions remained similarly low or decreased.