Case-cohort analysis of case-coverage studies of vaccine effectiveness.

Evaluation of vaccine field effectiveness may be performed by combining surveillance data on incident cases with an immunization coverage survey. Although many methods have been used for the analysis of studies of similar design, they are not always desirable or optimal. The authors discuss these approaches and propose use of a case-cohort analysis for such a study design when appropriate. The case-cohort analytic approach is illustrated with data from studies of a vaccine for Haemophilus influenzae type b (Hib) disease in children living on a southwestern Native American reservation during 1988-1993.