Development of combination vaccines

Breakthroughs in molecular biology, biochemistry, process development, immunology and related fields have provided the means for improving current vaccines and developing new ones. The increasing availability of these vaccines is providing the unprecedented opportunity to prevent serious infectious disease in different age groups and to significantly reduce associated morbidity and mortality. However, since the great majority of licensed and experimental vaccines in advanced clinical studies are injected, each new vaccine creates the need for additional needlesticks which could become so numerous as to discourage full compliance with immunization schedules. Therefore, the development of combination vaccines is a major way to assure compliance with immunization needs. The leading types of licensed and experimental vaccines which have been or may be made into combination vaccines will be described. In addition, key challenges common to the development of all combination vaccines will be discussed; these include pharmaceutical, immunological, clinical, regulatory, manufacturing, public health and marketing issues. In order to assure timely development and availability of such combination products, these issues must be integrated successfully early in a development program.