ACELLULAR PERTUSSIS VACCINES - THE RATIONALE FOR AN EFFICACY TRIAL INGERMANY

After concern about the safety of diphtheria-tetanus toxoid-whole cell pertussis vaccines (DTPw), the recommendation to vaccinate children w ith DTPw was withdrawn in 1974 in the former West Germany. This led pe rtussis cases to increase to an estimated 100,000 annually. Despite re newal of the vaccination recommendation in 1991, vaccine use remained low. The German health care structure assures regular contact between most children and pediatricians, This enabled the conduct of a large e fficacy trial with a diphtheria-tetanus toxoid-acellular pertussis (DT Pa) vaccine. Because a placebo-controlled trial was not ethically poss ible, a prospective household contact study with a blinded clinical fo llow-up was done. Possible study participants were screened by their p ediatrician, who also initiated diagnostic procedures. Clinical follow -up was done by another locally based but independent and blinded phys ician. Vaccine efficacy was calculated to be 89% (95% confidence inter val, 76.6%-94.6%). None of the identified confounding factors biased r esults in favor of the DTPa vaccine.