page 15 First, consider the numbet of addicional life years that would be saved if mea.sles vaccination were added to the Javanese program. The Michigan study estimated the incidence rate at zero for infants less than one and only 200 per chousand among children aged one to four. In the latter group the study assumed the case fatality rate to be 4.8% (0.5Z among the 20X treated and 5% among the 80% untreated). If measles vaccine is 60% effective as assumed in Table 1, then it will save 5.76 lives per thousand vaccinated (200 x .048 x .6). Assuming that 1,500 children are vaccinated per year just as they are entering the 1-4 age bracket where their life-expectancy is 52 years (from Table 2, column 3), the addition of measles vaccination would save an additional 449 life years per year in this Javanese rural population of 50,000 (5.76 x 1.5 x 52).

However, the incidence of neona.al tetanus in Java was estimated at 21.3 per thousand with a case fatality rate of 90%. Thus, removing the 2100 doses of t,.tanus toxoid given to the pregnant mothers (assumed 95% effective by Grosse et al, Appendix A, V.3) would increase deaths in the zero to one age group by 18.2 per thousand. For the 1,500 in this age group whose life expectancy is 48 years, the life-years lost would be 1,310 (18.2 x 1.5 x 48). The Michigan study did not include polio among the 31 diseases analyzed, possibly because its impact on mortality and morbidity was deemed small. Indeed in Ghana polio does not even rank among the top 25 contributors to life-days-lost (Ghana Health Assessment Teram, 1981, Table 2). As a rough approximation, assume that the Ghanaian figure of 1.2 days of life lost per person per year applies to Java as well. Then adding polio vaccination would save an additional 164 life years in the population of 50,000 Javanese (1.2 x 50,000 / 365.25), while requiring an a-iditional 18,300 vaccinations on the assuaption that the children getting DPT get polio vaccinations at the same time. Thus the net effect of these three adjustments to the Javanese - immunization program would be a loss of 697 life-years (449 + 164 1310) and an increase in the number of vaccinations by 17,700 (1500 + 18,300 - 2100). To arrive at an estimate of b for Java, subtract 697 from 1790, multiply the result by the number of days in a year and add 22,500 days of averted disability (from column 9 of Table 2) for a total of 421,700 LDS. Then divide this total by the 44,700 (27,000 + 17,700) vaccinations that would be required to achieve it. The resulting estimate is 9.4, a substantial reduction in average impact from the program defined by the Michigan study.[15] 2. Estimates of Life-Days-Saved Per Encounter. The impact of an immunization program is inherently easier to estimate than that of a VHW program, because effective immunization produces a measureable change in blood chemistry which accurately predicts whether an individual will ever contract the disease in question. In some cases sero-conversion correlates highly with an even more visible sign, a scar at the vaccination site. In contrast, the impact of VHWs on health can only be measured by observing a change in health status associated with their activites. Nevertheless the absence of information on the impact of VI W services on health status is surprising in light of the available experience with VHW projects. A review published in 1982, which limited itself to primary health care projects funded by the United States Agency for International Development, identified 52 such projects of which 42 used a VH W of one variety or another. However, the reviewers could find only "only five evaluations of health status located in