Individuals wishing to evaluate the effect on the ultimate rankings of adopting different assumptions on the magnitude of the disease burden can do so in crude fashion by adjusting the final APVPHB in accordance with their beliefs. For example, if they believe that the overall disease incidence is twice that used in the central analysis (but that rates for complications, sequelae, case-fatality rates, etc., are reasonable) the central analysis APVPHB value should be doubled. The rank of the new APVPHB value can then be determined. More complex disagreements with disease burden determination (e.g., favoring a different frequency of complications) requires recalculation of the disease burden estimates and the TDBV.

The bases for the various disease burden proportions that are judged to be vaccine preventable are described in Appendixes D-1 through D-19. The effect of alternative assumptions can easily be examined by substituting a new value in the calculation process shown in Table 7.4. Assumptions different from those in the central analysis may alter the ranking of vaccines. For example, 50 percent of the disease burden for hepatitis B vaccine is estimated to be preventable by delivering the vaccine at the usual WHO-EPI scheduled times. If vaccines were delivered universally at birth, some higher proportion would be preventable and the potential benefits would be raised proportionally.

The targeted population may markedly affect the potential expenditures. For example, delivery of the N. meningitidis vaccine to the entire birth cohort in the developing world (115.1 million births) would cost about $708 million. Focusing vaccine delivery on births in the African meningitis belt (13.1 million births) would reduce the cost by about 90 percent to $82 million. (Because this strategy would not protect against endemic or rare epidemic disease in other parts of the world, potential health benefits would also be less; see Appendix D-8).

Similarly, immunotherapeutic use of a vaccine for M. leprae—to curtail progressive disease in all recognized new cases—would cost $10.3 million as contrasted to immunoprophylactic use in the birth cohort at risk, which would cost $270 million. These strategies are, however, significantly different, and this commentary does not suggest that immunotherapy would be more “cost-effective.” To be useful, such a strategy would require substantially increased efforts at early case detection.

The committee believes that incorporating a discounting procedure for future health benefits and expenditures is justified because it reflects the preference for benefits achieved sooner rather than later (a basic concept in the establishment of a program of accelerated vaccine development). The effect of placing more or less weight on