Objective: To measure the efficacy of measles vaccination in a given geographical area.
Design: Population based case control study.
Setting: Medical Officer of Health area, Kotte.
Subjects: All children born after January 1985 and registered by the midwives of the area.
Results: Vaccine efficacy was 88.9%, the 95% confidence limits being 65.21% to 96.5%.
Conclusion: The method described is a suitable alternative to the more expensive serological estimates of vaccine efficacy.