We formulate the total expected cost of the epidemic in terms of the underlying costs associated with maintaining infected individuals until recovery, suffering death, and administering vaccinations. Let c 1 a,c,s ð Þ denote the cost associated with interventions involving susceptibles when S(t) = s. Here a is the fraction of susceptibles that are moved directly into an immune/recovered class, as by vaccination, and c is the threshold below which the intervention is discontinued. Letting c v denote the cost per unit, then