currently occurs only sporadically among travelers returning from areas where the disease is endemic and/or rarely in limited local outbreaks secondary to their return. With such infrequent and narrow threats, efforts at vector control have proved adequate U.S. public health responses.
However, malaria is an enormous problem elsewhere, with a high morbidity and mortality burden (3 million deaths per year). The emergence of multiple-drug-resistant variants of Plasmodium, along with insecticide resistance among the vectors of malaria coupled with environmental impediments to vector control, are all factors that make a vaccine approach to malaria control a matter of high priority when assessed from a global perspective. Furthermore, the scientific status of malaria vaccine research promises that exciting progress may be at hand (IOM, 1996b). Therefore, although the mandated U.S. focus of the project does not include malaria, a global overview would surely place it at a high level in a list of priorities—not only malaria but, indeed, all parasitic diseases (e.g., schistosomiasis, leishmaniasis, and Chagas disease) were excluded from the committee’s analysis despite their high global toll on health. Finally, some diseases are of marginal importance to U.S. citizens except during military service.
The committee has included in its analysis candidate vaccines that would be of great international benefit in addition to that gained with domestic use. Its analysis, however, does not include benefits to be gained by such international use. An analysis that included international disease burden might well have significant impact on the results (ranking or grouping into broad categories of benefits) of the modeling. For example, the resurgence of tuberculosis in the United States, and especially the emergence of multiple-drug-resistant strains, is of sufficient concern to raise it to a high level of concern even in U.S. terms. Globally, however, it dwarfs all other pathogens, causing 3 million deaths per year. It is the proximate cause of approximately half of AIDS deaths in Africa. Along with the emergence of HIV in Asia, where tuberculosis is highly prevalent, it is likely to assume even greater dominance as the most lethal infectious pathogen of humans.
Similar changes in priority might be seen for viral and bacterial respiratory infectious diseases. Improved vaccines against RSV, Streptococcus pneumoniae, and group A streptococci, among other agents, would also be included on a global priority ranking. Likewise, enteric viruses such as rotavirus and bacteria such as Shigella are important contributors to mortality worldwide.
In addition to the explicit inclusion criteria based on the charge to discuss candidate vaccines of domestic health importance and feasibility of licensure, the committee seriously considered candidate vaccines for reasons other than judgment about disease burden and likelihood of development within 20 years.