Vaccinology in practical perspective.

The nearly two centuries of success and failure in vaccinology have been superceded by an era of new opportunity employing hybridoma, recombinant, directed genetic alteration, and synthetic chemical technologies. Vaccines against a large number of infectious disease agents are now possible and they may be made practically useful by incorporating many relevant epitopes in complex "polytopic" vaccines. Though the technologies are well laid, hurdles still remain and these involve the need for understanding immunity in molecular terms. Developed countries typically underutilize vaccines even though resources are adequate. In Third World countries, where the need is greatest, there is least use because of the lack of resources. In pursuing vaccinology for Third World application, a balance needs to be sought, in the practical sense, between the amount of funds allocated to research and development and the amount allocated to utilization, lest vaccines be wastefully created that can never be used. Inclusion of the greatest possible number of needed immunodeterminants in the fewest number of vaccines is critical to practical application in developed as well as in developing countries.