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BOX 5–1 Steps Used in Calculation of Vaccine-Related Health Benefits for a Specific Condition

  • Develop morbidity scenarios, including estimate of percentage of cases represented by each scenario.

  • Calculate quality-adjustment weights for each health state in each scenario.

  • Calculate discounted quality-adjusted life expectancies.

  • Establish age-specific incidence and death rates for the condition.

  • Calculate average age at onset and average age at death.

  • Calculate average interval between vaccination and onset of illness.

  • Calculate average interval between age at onset of illness and age at condition-related death.

  • Calculate life expectancy at average age at onset and average age at death.

  • Calculate a baseline quality-adjustment weight for the population.

  • Adjust the health state weights to reflect the population baseline.

  • Calculate discounted QALYs for each health state with and without the impact of condition-related morbidity.

  • For each morbidity scenario, sum the QALYs for the component health states.

  • For each morbidity scenario, subtract QALYs with the condition from QALYs without the condition (i.e., calculate the condition-related QALYs lost).

  • Weight the condition-related QALYs lost in each scenario by the percentage of cases represented by that scenario and sum across all scenarios.

  • Multiply the sum of QALYs lost by the total number of cases for the condition.

population were used to measure QALYs with the intervention. To measure the impact of mortality and lifetime impairment, standard life table values were “quality adjusted” for the average health status of the population and discounted to their present value. Described here are the population-level quality adjustments used in the committee’s analysis and the calculation of the discounted quality-adjusted life table values.

Population-Based Quality-Adjustment Weights The analysis takes into account the underlying average health status of the population, independent of a specific condition or use of a candidate vaccine. Although an individual might be considered to experience periods of perfect health, represented by a quality-adjustment weight of 1.0, the health status of a population will reflect a range of individual levels of health status and should not be represented by a quality-adjustment weight set at 1.0. This average health status in the population is assumed to be the maximum health status level that can be achieved by use of any of the vaccines considered in the committee’s analysis. To represent the average health status of

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