Incorporating Cholera Vaccine Herd Protection into Economic Cost-Benefit and Cost-Effectiveness Models

Ignoring the indirect effects of vaccination has led to two types of inaccuracies in cholera vaccine policy analysis in endemic settings. First, when herd protection is ignored, the social benefits and cost-effectiveness of vaccination programs are underestimated, such that the programs are rarely considered to be a wise use of scarce public health resources. Once vaccine herd protection is included, use of the vaccine can satisfy both social welfare objectives and benchmark cost effectiveness criteria. Second, design recommendations to implement programs considered most attractive without accounting for the effect of herd protection may not allow the capture of the greatest social benefits. The analysis summarized in this paper demonstrates that it is possible to account for herd protection in both cost-effectiveness and cost-benefit calculations. In the former case, however, it does pose significant interpretation challenges. When herd protection is incorporated into a cost-effectiveness model, cost-effectiveness measures such as costs per DALY avoided become a function of vaccination coverage. When this is the case, there is no obvious decision objective in a cost-effectiveness analysis. Cost-benefit metrics, on the other hand, provide a clear economic argument for when to pursue vaccination efforts and how to design them. More sophisticated measurements of the economic benefits of vaccination should therefore become standard practice when evaluating the potential of vaccination programs.