RANDOMIZED COMPARISON OF REACTOGENICITY AND IMMUNOGENICITY OF 2 WHOLE-CELL PERTUSSIS VACCINES

Objective. To compare prospectively the reactogenicity and immunogenic ity of two licensed whole-cell pertussis vaccines. Methods. We conduct ed a prospective, randomized, double-blinded assessment of two license d whole-cell pertussis vaccines with diphtheria and tetanus toxoids th at were included in a multicenter trial evaluating 13 acellular pertus sis vaccines. Infants were immunized at 2, 4, and 6 months of age with a single lot of Lederle (309 infants) or Massachusetts Public Health Biologic Laboratories (MPHBL; 94 infants) vaccine. Results. The group receiving the Lederle vaccine demonstrated significantly higher antibo dy titers to pertussis toxin by enzyme-linked immunosorbent assay (ELI SA) and by the Chinese hamster ovary cell pertussis toxin neutralizati on assay, and to fimbrial antigens by ELISA, as well as higher mean ag glutinin titers. In contrast, the group receiving the MPHBL vaccine de monstrated higher ELISA antibody levels to filamentous hemagglutinin a nd pertactin. Similar differences were observed in the proportions of vaccinees seroconverting to these antigens. Rates of systemic and loca l reactions were relatively low for both vaccines. Although the Lederl e product had substantially lower reactogenicity in this study than pr eviously reported for that vaccine, the MPHBL vaccine was significantl y less reactogenic in nearly all clinical categories. Conclusion. The two whole-cell vaccines demonstrated statistically significant differe nces in postimmunization antibody levels to all six evaluated pertussi s antigens. Whether these statistically significant differences in ant ibody levels have clinical relevance is not clear. Rates of nearly all local and systemic reactions were significantly lower among the MPHBL group than the Lederle group. Licensed whole-cell diphtheria-tetanus- pertussis vaccines produced by different manufacturers cannot be assum ed to be similar in reactogenicity or immunogenicity.