Economic evaluation of vaccination.

With increasing expenditures in healthcare, in absolute terms as well as in relative terms, interest in the efficiency of certain interventions in healthcare has also increased. Faced with the limitations of the healthcare budget, budget holders try to find the optimal way of dividing their funds over different healthcare provisions, without discarding human and medical considerations. In economic terms, this process could be called the 'optimal allocation of scarce resources over the inputs of a function of production'. The means of production would then be 'the provision of healthcare', whereas the output would be 'improvement of health'. Clearly choices have to be made with regard to spending the healthcare budget. One of the instruments that can help in making such choices is the economic evaluation. In economic evaluations of vaccinations, different vaccination strategies are defined. The consequences in terms of costs and effects of each strategy are being calculated and compared with a reference strategy, which is often the nonintervention strategy, i.e. 'no vaccination'. According to the way in which the benefit or the output of vaccination-'improvement of health'-is measured, a distinction is made between various methods of economic evaluation: in a cost-effectiveness analysis, health gains are measured in natural units (e.g. prevented infections, prevented illness days, life-years gained, etc.); in a cost-utility analysis, the quality of the health gains is taken into account (e.g. quality-adjusted life-year); and in a cost-benefit analysis, health gains are converted into monetary units. Costs can be divided into direct and indirect costs. Direct costs are directly related to medical treatments (medication, laboratory tests, consultations, etc.) or to vaccination (e.g. purchasing price of the vaccine, costs for administering the vaccine, treatment of side effects, etc.). Costs indirectly related to treatments and vaccination are mainly costs of lost productivity due to disease morbidity or mortality, and opportunity costs. In comparison with other vaccine-preventable infections, influenza vaccination for the elderly seems acceptable from an economic point of view (about $US650 per life-year gained, in 1981). Cost-effectiveness ratios of other vaccinations range from about $US720 per life-year gained for universal hepatitis B vaccination to about $US190,000 per life-year gained for universal Haemophilus influenzae type by vaccination. Because of differences in methods, the representation of results, and country-specific parameters, different economic evaluations of the same vaccination strategy may show divergent results. Therefore, until sufficient standardisation of economic evaluations exists, comparisons of the sort we are making here should be interpreted with prudence.