Efficiency in a population of voluntary vaccination against communicable enzootic disease in bovine holdings: study by coupling an epidemiological model and an economic model.

For transmissible diseases, individual management of the disease reduces the probability for other herds to be infected. When the disease is not regulated, the choice of the control measures is left to farmers, who did not necessarily take into account the collective effect : individual management of transmissible diseases creates a positive externality. Besides, the decrease in risk due to the positive externality may have an impact on the individual choices. The objectives of this study are to evaluate the effectiveness at a regional level of voluntary vaccination. We developed a dynamic deterministic model, based on a decision model interacting with an epidemiological state transition model. It determines the proportion of farmers who vaccinate and the prevalence of infected herds over time. The model shows that voluntary vaccination cannot eradicate the modeled disease. Incentives for vaccination decrease the prevalence but do not result in eradication of the disease.