### A bayesian framework for the ratio of two Poisson rates in the context of vaccine efficacy trials

In many applications, we assume that two random observations and are generated according to independent Poisson distributions $\left(\lambda S\right)$x1d4ab;() and $\left(\mu T\right)$x1d4ab;() and we are interested in performing statistical inference on the ratio = / of the two incidence rates. In vaccine efficacy trials, and are typically the numbers of cases in the vaccine and the control groups respectively, is called the relative risk and the statistical model is called ‘partial immunity model’. In this paper we start by defining...