Research on both malaria and other infections diseases has generated new approaches to immunization that offer great promise for malaria vaccines. Nucleic acid vaccines, proteosomes, and several new adjuvants are examples of technologies that may be appropriate for the next generation of malaria vaccines.
Market forces for developing malaria vaccines, while not appreciated, are potentially vigorous, and growing on a global scale.
As with the development of any commercial product, a clearly identified market is essential. Remarkably little effort has been directed toward characterizing potential global markets for different malaria vaccines. The traditionally most attractive markets have been thought to be the military and “traveler” markets of North America and Europe—the vast emerging middle classes in South and Central America, Africa, India, and Southeast Asia, where the risk of malaria is widely recognized, have been largely overlooked. Nevertheless, the type of vaccine suitable for travelers, which may be quite expensive, could also find a vigorous and profitable market within these populations. It seemed likely to workshop participants that analyses of potential consumer populations would reveal a market of hundreds of millions of dollars annually, which would render a malaria vaccine an economically sound investment for a pharmaceutical company. The neediest populations, however, still comprise the poor and very large populations of Asia and Sub-Saharan Africa, which suffer disproportionate death and morbidity from malaria, yet have limited ability to pay for vaccines. Workshop participants recognized that a vaccine for reducing mortality in these populations, while potentially more feasible, must also be affordable. Large international agencies such as the World Health Organization, UNICEF, and the bilateral assistance agencies, which would be the most likely purchasers and distributors of vaccines for these populations, would have to do so through pricing and delivery agreements with vaccine manufacturers. Analyses of these markets, including cost-effectiveness studies of vaccine price supports compared with other methods of malaria prevention and control, are essential for informed decision-making by industry and the public sector.
Immunization-challenge studies in humans offer a means of rapid evaluation of efficacy for some types of malaria vaccines.
Obtaining evidence of safety and efficacy in the target population is a critical step for any new vaccine candidate. Early in the development process, preerythrocytic and sexual-stage malaria vaccines can be safely tested for efficacy through experimental challenge of a small number of tightly controlled and monitored volunteers recruited under informed consent procedures. Such small-scale trials ensure that only the most promising vaccine strategies proceed to more elaborate and expensive field trials. The expertise and technical support required to perform this procedure are available in academic centers and in Department of Defense laboratories.