Target populations for the vaccines are described in the relevant appendixes and briefly outlined in Table 5.1. The number of new potential vaccine recipients entering the target population each year must be determined to calculate the number of adverse effects and the costs associated with each vaccination program. These calculations are based on the envisaged target population and the 1984 population projections (Bureau of the Census, 1984). Background information used to determine the number of new potential recipients of each vaccine is shown in Table 7.1.

For each disease, estimates of vaccine preventable illness are derived from an examination of the distribution of the disease burden; the envisaged target population; the characteristics of the vaccine (e.g., the number of doses); the likely age of vaccine delivery; and for some diseases (e.g., hepatitis B and influenza), the proportion of the disease falling in the identified high-risk group.

Estimates of vaccine preventable illness for each disease are discussed and included in Appendixes C through P. These estimates, based on steady-state utilization, are derived from disease burden estimates judged to reasonably represent 1984 levels (see Chapter 4 and below).

Calculations of morbidity, mortality, and costs assume that the effects of trends in disease burden and population size (between 1984 and the achievement of steady-state benefits) would not be of sufficient magnitude to obscure differences between diseases. The effects of such trends could be examined, if desired, within the model proposed. These assumptions apply only to diseases under study and the current population projections: if other disease candidates are added to the list, the assumptions should be re-examined. Because of the trend towards greater numbers of individuals in the 25–59 years and 60 years and over age groups, the major effect of adopting these assumptions would be to somewhat underestimate the benefits of vaccines reducing disease in these age groups, assuming incidence rates remain constant.

The maximum number of adverse reactions is calculated from the predicted incidence of adverse reactions (Table 5.1), assuming delivery of the required number of doses to the annual number of new potential vaccinees (Table 7.1). IME values appropriate for the conditions