REDUCED CHILDHOOD MORTALITY AFTER STANDARD MEASLES VACCINATION AT 4-8MONTHS COMPARED WITH 9-11 MONTHS OF AGE

Objective-To evaluate the impact on mortality of standard Schwarz meas les immunisation before 9 months of age. Design-Children vaccinated in 1980-3 at 4-5, 6-8, and 9-11 months of age were followed to migration , death, or the age of 5 years. Setting-One urban district and nine vi llages in two rural areas of Guinea-Bissau. Subjects-307 children vacc inated at 4-8 months and 256 at 9-11 months. Main outcome measures-Mor tality from 9 months to 5 years of age for children immunised at 4-5, 6-8, and 9-11 months. Results-Mortality was significantly lower in chi ldren vaccinated at 6-8 months than at 9-11 months (mortality ratio=0. 63, (95% confidence interval 0.41 to 0.97), p=0.047). As vaccination w as provided in semiannual or annual campaigns it is unlikely that age at vaccination reflected a selection bias. The trend was the same in a ll three study areas. Improved survival after early immunisation was n ot related to better protection against measles infection. With a Cox multivariate regression model to adjust for age, sex, season at risk, season at birth, measles infection, and region, children vaccinated at 4-8 months had a mortality ratio of 0.61 (0.40 to 0.92, p=0.020) comp ared with children vaccinated at 9-11 months. Reimmunised children ten ded to have lower mortality than children who received only one vaccin e (0.59 (0.28 to 1.27, p=0.176)). Conclusion-Standard measles vaccinat ion before 9 months is not associated with higher childhood mortality than is the currently recommended strategy of immunising from 9 months , and it may reduce mortality. This has implications for measles immun isation strategy in developing countries.