Objective
To compare the safety and immunogenicity of a three-component acellular pertussis (DTaP) vaccine containing pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin with whole-cell pertussis (DTwP) vaccine in 4- through 6-year-old children.
Participants
One hundred seventy-two healthy 4-through 6-year-old children previously immunized with the DTwP vaccine at or near 2,4,6, and 18 months of age.
Interventions
Prevaccination serum samples were obtained on all study participants. One hundred twelve children received 0.5 mL of the DTaP vaccine intramuscularly. Fifty-three children received 0.5 mL of a commercially available DTwP vaccine intramuscularly. Approximately 30 days following vaccination, additional serum samples were obtained.
Measurements
Parents monitored adverse reactions for 7 days following immunization. Significantly fewer children in the DTaP group reported temperatures of greater than 38.1°C and an area of redness of more than 10 mm and moderate-to-severe pain at the injection site.
Results
Antibody responses to PT, FHA, pertactin, and diphtheria and tetanus toxoids were measured by enzyme-linked immunosorbent assay. Among subjects who were seronegative prior to vaccination, response was defined as the detection of antibody levels following vaccination; among children with detectable antibody levels prior to vaccination, in terms of the rise in antibody titers. Data using a twofold and a fourfold rise in antibody titers as criteria to define response were evaluated. Children in the DTaP group had significantly greater increases in geometric mean titers of antibodies against PT, FHA, and pertactin. Over 90% of the DTaP group responded to PT, FHA, and pertactin according to the criteria of both the twofold and the fourfold rise in antibody titers. Significantly fewer of the DTwP group responded to PT, FHA, and pertactin with at least a fourfold rise in antibody titers. When analyzing subjects with at least a twofold increase in antibody titers, a statistically significant difference remained in regard to anti-FHA antibodies. All study subjects had protective antibody titers against diphtheria and tetanus toxoids following vaccination. The geometric mean titer of antibodies against tetanus was significantly greater in the DTwP group than in the DTaP group.
Conclusion
The three-component DTaP vaccine administered as a booster immunization in 4- through 6-year-old children produced less fever and less redness and pain at the injection site than the DTwP vaccine and was as immunogenic as the DTaP vaccine.
(Arch Pediatr Adolesc Med. 1994;148:503-507)
Elmwood Pediatric Associates; Pennridge Pediatric Associates
From the University of Rochester Medical Center (Drs Annunziato and Pichichero) and Elmwood Pediatric Associates (Dr Pichichero), Rochester, NY, St Christopher's Hospital, Philadelphia (Drs Rothstein and Bernstein and Pennridge Pediatric Associates), and Pittsburgh (Pa) Pediatric Research Inc (Drs Blatter and Reisinger).
