ABSTRACT
The chapter first considers cohort studies with parallel vaccinated and unvaccinated groups, in which all individuals are followed for the same period of time. Then the chapter goes on to consider cohort studies in which follow-up times may vary between individuals. Next, the chapter discusses cohort studies undertaken within households; such studies are also called household contact studies. A summary table is provided at the end of the chapter, listing the various designs and some of their key properties.
