Efficacy and cost-effectiveness of influenza vaccination of the elderly in a densely populated and unvaccinated community.

For economic reasons, the few influenza vaccination programs seen in developing countries are aimed at the high-risk elderly. To evaluate its efficacy and cost-effectiveness, we conducted a 2-month influenza vaccination campaign in southern Taiwan's A-Lein township for all the elderly. Significant differences in hospitalization and mortality between the vaccinated and unvaccinated groups were found. Age, sex, and risk group were significant for hospitalization and mortality, but only vaccination was significant for prevention. Savings for each person vaccinated were at least three times the cost of vaccination. We strongly recommend that all the elderly-not only high-risk elderly--receive an annual influenza vaccination.