COMPARATIVE EFFICACY OF THE LEDERLE TAKEDA ACELLULAR PERTUSSIS COMPONENT DTP (DTAP) VACCINE AND LEDERLE WHOLE-CELL COMPONENT DTP VACCINE INGERMAN CHILDREN AFTER HOUSEHOLD EXPOSURE/

Background. A household contact sub-study was performed as part of a p rospective, cohort pertussis vaccine efficacy trial in Germany. Design . Infants received four doses of either the Lederle/Takeda acellular p ertussis component diphtheria-tetanus toxoids (DTP) vaccine (DTaP) or Lederle whole-cell component DTP vaccine at 3, 4.5, 6, and 15 to 18 mo nths of age (Wyeth-Lederle Vaccines and Pediatrics, Pearl River, NY). An open control group received three doses of diphtheria and tetanus t oxoids vaccine (DT) at 3, 4.5, and 15 to 18 months of age. Vaccine eff icacy rates were calculated using a number of principal and ancillary case definitions for primary, secondary, and noncases by analyzing sec ondary attack rates in study infants after exposure to pertussis in th e household using 7- to 28- and 7- to 42-day postexposure observation periods and the inclusion and the exclusion of noncases who received m acrolide antibiotics or trimethoprim-sulfamethoxazole during the expos ure period. Results. During a 3.5-year study period, 10 271 infants (D TP or DTaP, n = 8532; DT, n = 1739) were enrolled and actively followe d along with all household members for cough illnesses. Depending on t he case definition, 160 to 519 household exposures to pertussis were i dentified. In general, secondary attack rates in DT recipients were lo w and this was primarily because of the frequent use of antimicrobial prophylaxis. Using the principal case definitions and the exclusion of noncases who received macrolide antibiotics or trimethoprim-sulfameth oxazole during the exposure period and the 7- to 42-day observation pe riod, the efficacy of DTP against cough illness of greater than or equ al to 7 days duration caused by Bordetella pertussis was 84% (95% conf idence interval [CI] = 65-93) and that of DTaP was 58% (95% CI = 30-75 ). Using similar criteria, the efficacy against typical pertussis (gre ater than or equal to 21 days of cough with either paroxysms, whoop, o r posttussive vomiting) was 94% (95% CI = 77-99) and 86% (95% CI = 62- 95) for DTP and DTaP, respectively. The efficacy against any cough ill ness (with or without) laboratory confirmation was 54% (95% CI = 32-69 ) and 38% (95% CI = 13-56) for DTP and DTaP, respectively. Conclusion. This household contact substudy within our cohort study, with active investigator-generated surveillance, was a severe test of vaccine effi cacy. Both vaccines (DTP and DTaP) are better at preventing typical pe rtussis than mild illness. When case definitions similar to those in o ther recent trials are used, the Lederle/Takeda vaccine has an efficac y similar to other multicomponent DTaP vaccines.