Economic evaluation of vaccination against influenza in New Zealand.

The objective of this study was to evaluate the costs and benefits of influenza vaccination for the population aged 65 years and over, from the perspectives of individuals and health insurers, government and society. The annual incremental direct medical costs and benefits of influenza vaccination (compared with the nonvaccination, or 'do nothing', option) were evaluated using New Zealand healthcare resource usage and unit cost data [in 1992 New Zealand dollars ($NZ); $NZ1 = $US0.5458, June 1992] applied to cohort studies reported in the literature. The costs and benefits to society as a result of vaccination of people aged 65 years and older (20% of people in this age group are currently vaccinated) were estimated to be: (i) additional direct medical costs of vaccination of $NZ1.42 million [$NZ17.78 per vaccination]; (ii) direct medical costs avoided of $NZ5.35 million ($NZ67.18 per vaccination); and (iii) net benefits of $NZ3.93 million ($NZ49.40 per vaccination). The direct medical costs avoided per dollar cost of vaccination were $NZ1.04 for individuals, $NZ4.69 for government and $NZ3.78 for society as a whole. If the vaccination uptake for this group is increased in 20% increments, the net benefit to society increases by a further $NZ3.93 million per year at each step. If the economic evaluation is extended to include vaccination of at-risk individuals under 65 years of age, net benefits to society increase by 15%. Influenza vaccination for people aged 65 years and over is cost effective from the perspective of society, government and the individual. If the vaccination rate for at-risk individuals in New Zealand could be increased to 60%, the net benefits reported in this study would increase by 200%. However, the costs of promotion and education to achieve this vaccination rate would need to be deducted from the net benefits. Strategies to increase the vaccination rate include altering the cost of vaccinations to the individual, intensifying education and promotion programmes, and changing the mode of delivery.