  A general stochastic model for susceptible -> infective -> recovered (SIR)
epidemics in non homogeneous populations is considered. The heterogeneity is a
very important aspect here since it allows more realistic but also more complex
models. The basic reproduction number $R_0$, an indication of the probability
of an outbreak for homogeneous populations does not indicate the probability of
an outbreak for non homogeneous models anymore, because it changes with the
initially infected case. Therefore, we use "individual $R_0$" that is the
expected number of secondary cases for a given initially infected individual.
Thus, the effectiveness of intervention strategies can be assessed by their
capability to reduce individual $R_0$ values. Also an intelligent vaccination
plan for fully heterogeneous populations is proposed. It is based on the
recursive calculation of individual R0 values.
