Challenges and solutions in the development of vaccines against emerging and neglected infectious diseases.

Emerging and emergent infectious diseases (EIDs) represent a significant and growing cause of morbidity and mortality with increased potential for pandemics due to globalization and international trade. Challenges remain to the approach toward vaccine development for EIDs. This Special Feature explores areas related to vaccine development and testing, including unique challenges posed in the developing world. Vaccines against multiple pathogens spanning a number of viral families are explored with respect to past activities through to future commercialization. Cost drivers balanced against clinical need are discussed and unique challenges posed by rare diseases are considered.