Print PageThe vaccination threshold required to interrupt transmission of an immunizing infection like measles is predicted by epidemic theory to depend only on transmission rates. However, fully exploring optimal strategies requires that we also consider economic constraints. Assuming that vaccination will have to continue after disease elimination to maintain herd immunity in the face of disease re-emergence, we look for optimal vaccination covereage that minimizes combined infection and vaccination costs.
Results/Conclusions
Surprisingly, we find that the optimum for disease control in a single population is determined mainly by relative costs of infection and control, rather than transmission rates. Adding a spatial dimension, which precludes elimination unless it can be achieved globally, can reduce or increase optimal vaccination levels depending on the balance of costs and benefits. For weakly coupled populations, local optimal strategies (Nash optima) agree with the global cost-effective strategy; however asymmetries in costs can lead to divergent control optima in more strongly coupled systems – in particular, strong regional differences in costs of vaccination can preclude local elimination even when this is locally optimal. We conclude by delineating when it is locally optimal to share vaccination resources with other populations.
