ABSTRACT
The chapter begins with traditional case-control studies, in which the controls are chosen among non-cases. The chapter then goes on to consider variants of the case-control method in which controls can also be or become cases. Next, the chapter discusses two special case-control methods: the test-negative and indirect cohort methods. It goes on to describe the screening method, in which controls are replaced by vaccine coverage data, which makes the method particularly easy to apply provided reliable coverage data are available. A summary table is provided at the end of the chapter, listing the various case-control designs and some of their key properties.
