Appendix 2—figure 1. Experimental transmission study to demonstrate vaccine efficacy Both phases consist of two experimental groups with ${\displaystyle 52(4N)}$ co-housed animals.

Within each experimental group there is a balanced number of seeder ($26,2N$) and sentinel animals ${\displaystyle (26,2N)}$. 50% of the sentinel animals are vaccinated (${\displaystyle N=13}$) and 50% unvaccinated controls ${\displaystyle (N=13)}$. For Phase I the seeders (${\displaystyle S_R}$) are recruited from the field. At the end of Phase I, the exposed control animals and vaccinated animals are group together and used as the seeder animals (${\displaystyle S_U}$ and ${\displaystyle S_V}$ respectively) and set in contact with a fresh set of (uninfected) sentinels.