Table 1.

Illustrative example of a two-stage randomized placebo-controlled cholera vaccine trial based on data from Ali et al. (2005). Group assignment corresponds to 50% or 30% vaccine coverage (from Hudgens and Halloran 2008).

Group	Group assignment (% vaccinated)	Vaccine recipients		Placebo recipients
		Total	Cases	Total	Cases
1	50	12541	16	12541	18
2	50	11513	26	11513	54
3	30	10772	17	25134	119
4	30	8883	22	20727	122
5	30	5627	15	13130	92