EFFECT OF GENDER, RACE, AND PARENTAL EDUCATION ON IMMUNOGENICITY AND REPORTED REACTOGENICITY OF ACELLULAR AND WHOLE-CELL PERTUSSIS VACCINES

Objective. To determine whether gender, race (black or white), or leve l of parental education influenced serologic responses or reporting of clinical reactions after immunization with acellular (DTaP) or whole- cell (DTP) pertussis vaccine with diphtheria and tetanus toxoids combi ned. Methods. Healthy infants were prospectively randomized to receive one of 13 DTaP, Lederle DTP, or another DTP. Parents recorded the occ urrence of adverse reactions for 2 weeks after each inoculation. Sera obtained before the first immunization and 1 month after the third imm unization were analyzed for antibody to pertussis toxin, filamentous h emagglutinin, fimbriae, and pertactin (PRN). Chinese hamster ovary cel l pertussis toxin neutralization assays were performed, and levels of agglutinating antibodies determined. Results. Prevaccination antibody levels did not differ by race, gender, or parental education. Postimmu nization geometric mean titers (GMTs) were strongly and consistently a ssociated with race. For both DTaP and DTP and for every included anti gen, postimmunization GMTs were about twice as high for black as for w hite infants. Among DTaP recipients, these differences were significan t for pertussis toxin, Chinese hamster ovary cell pertussis toxin neut ralization assay, filamentous hemagglutinin, PRN, and agglutinins; amo ng the much smaller sample of WCL recipients, the differences achieved or approached statistical significance for agglutinins, PRN, and fimb riae. These findings were confirmed by regression analyses that contro lled for gender, parental education, study site, and preimmunization a ntibody level. Reported reactions were not correlated with parental ed ucation level and showed no material correlation with gender. Black in fants were reported to have had more pain than white infants after rec eiving WCL and DTaP and were reported to be more fussy after receiving WCL. Conclusions. The consistently higher postimmunization GMTs among black infants seems to be a real finding for which we have no explana tion; the infants did not significantly differ by race in vaccine assi gnment, preimmunization antibody levels, age at immunization, or inter val from immunization to phlebotomy. These observations should be conf irmed and further evaluated in future pertussis vaccine trials. Report ed differences by race in pain and fussiness after receiving WCL might reflect chance, differences by race in the occurrence of reactions, o r differences by race in the reporting of reactions.