Quality control of diphtheria tetanus acellular pertussis combined (DTaP) vaccines in Japan.

Diphtheria tetanus acellular pertussis combined (DTaP) vaccines have been successfully used in Japan by controlling their potencies and toxicities with animal models. In accordance with the recent practical introduction of DTaP vaccines of various formulations, a question has been raised in other nations as to the efficacy of a quality control system based on animal tests and standard preparations. The World Health Organization issued its guidelines on the production and quality control of acellular pertussis vaccines in 1998 along with the concept of quality control by ensuring that production lots were consistent with clinical trial lots, rather than by comparing them with standard preparations in traditional laboratory tests. However, because it is not feasible to evaluate the combined use of vaccines from different manufacturers in a clinical study, the alternative trend of quality control may give rise to a difficulty in rationalizing the practical immunizations to use vaccines of different brands in a mixed consequence. A standardized national regulation system to ensure the equivalence of approved products would be essential for such an immunization practice. The success of the Japanese DTaP vaccination suggests the possibility of an effective quality control of DTaP vaccines by means of standardized test systems.