Cost-benefit analysis of vaccination against tick-borne encephalitis among French troops

French troops are exposed to tick-borne encephalitis (TBE) during their tours of duty in the Balkans. This disease, potentially serious because of its lethality and morbidity, has an effective vaccination. The epidemiological characteristics of TBE in the Balkans are not well known.

In order to provide the French Department of Defence with arguments on the utility of vaccinating troops on missions in this area of Europe, we conducted a cost-benefit study.

Through a decision analysis, we estimated the net benefit of a three-injection vaccination programme for all French military personnel in the Balkans versus no vaccination during a period from 2004 to 2014. We used a review of the literature to estimate the parameters necessary for the present study: the disease's morbidity and death incidence rate; the disease's sequelae; and the adverse effects of the vaccination. The initial hypothesis of the seroconversion rate of TBE in the Balkans was 834 per 100,000 person-years. Human life was valued in Euro (year 2004 values) by calculating the amounts paid by the French Department of Defence to military personnel in case of disabling sequelae and to their heirs in case of death.

The net benefit was negative: -5.68 million Euro. The vaccination programme's cost was 10.05 million Euro. 121 cases of TBE could be prevented by this vaccination; however, the sensitivity analysis showed that the results are closely related to the incidence of the disease.

Very high incidence rates of TBE were initially hypothesised compared with what has actually been reported. As a result, the vaccination programme against TBE for French military personnel should not be implemented unless the objective of the armed forces is to prevent all cases of TBE and they are willing to assume the cost of doing so.