ROLE OF IMMUNIZATIONS IN THE RECENT DECLINE IN CHILDHOOD MORTALITY AND THE CHANGES IN THE FEMALE MALE MORTALITY RATIO IN RURAL SENEGAL/

In early 1987, immunizations were introduced to an isolated area of ea stern Senegal where there had previously been no regular immunizations , Since immunizations were the only change introduced in the area duri ng this period, this allowed the authors to study the impact of immuni zations on mortality in different age groups and the possible interact ion with sex differences in mortality. They compared mortality rates f or the 6 years before and the 6 years after the introduction of immuni zation. Neonatal mortality declined 31% (95% confidence interval (CI) 17 to 43); between 1 and 8 months of age, the reduction was 20% (95% C I -2 to 37); and between 9 and 59 months of age, mortality declined 48 % (95% CI 39 to 56), Excluding acute measles deaths, the reduction was 16% (95% CI -8 to 35) between 1 and 8 months of age and 32% (95% CI 2 0 to 43) between 9 and 59 months of age. The decline was stronger in v illages that maintained high coverage after the initial national campa ign, whereas mortality increased again in the villages where the cover age declined. Since the reduction in mortality was most marked after 9 months of age, measles immunization is likely to have been the most i mportant vaccination. Both female and male mortality declined but not equally quickly. The reduction in mortality in the neonatal period was significantly greater in males than in females, resulting in an incre ase in the female/male mortality ratio from 0.64 (95% CI 0.50 to 0.83) to 0.96 (95% CI 0.71 to 1.30), p = 0.04. After 9 months of age, the r eduction in mortality was somewhat greater in females than in males, r esulting in a decrease in the female/male mortality ratio from 1.04 (9 5% CI 0.85 to 1.28) to 0.79 (95% CI 0.62 to 1.02), p = 0.10.