standard analysis depending on the change in delivery costs relative to the change in health care costs saved.

In summary, the hypothetical cases discussed above illustrate key factors that influence the cost per QALY gained with a new vaccine. These include the following:

• the number of vaccinees compared to the number of cases,

• the interval between the time of vaccination and the time at which disease is averted (i.e., the time at which the vaccinee experiences health benefits and savings in costs of care are realized),

• the number of QALYs to be gained by protection from disease for one age group compared with that for another age group (for the same number of calendar years), and

• mortality or long periods spent in a disabled state.

The committee was not charged to recommend which candidate vaccines should be developed. It has focused on developing a conceptual framework and a quantitative model for that framework to aid researchers and policymakers in planning research and development efforts for the plethora of candidate vaccines that have emerged over the last 10 years. As described in a preceding section, this model can aid policymakers in planning for use of new vaccines once licensed.

The primary measure used to report these results is a cost-effectiveness ratio of cost per QALY gained based on the annualized present value of the component costs and QALYs. As described in Chapter 3, there were many considerations in choosing these 26 diseases for which a vaccination strategy was considered feasible and appropriate. The committee chose a range of conditions (in terms of factors such as target populations, incidence of disease, and health states) for which a vaccination strategy might be used. The committee expected that the final results of the exercise would range widely.

The candidate vaccines fall into four reasonably distinct groupings or levels: candidate vaccines that would save money and QALYs; candidate vaccines that would require small costs (<$ 10,000) for each QALY gained; candidate vaccines that would require modest yet reasonable costs (<$100,000) for each QALY gained; and candidate vaccines that would require large costs (more than and much more than $100,000) per QALY gained.