Research on the control of influenza has traditionally been conducted within the paradigm of epidemiology, with little involvement of economics. The purpose of this K25 grant proposal is to develop a didactic training and research program that will enable Dr. Byung-Kwang Yoo to become an independent investigator in economic epidemiology of vaccine-preventable diseases, particularly influenza. Economic epidemiology aims at offering unique insights to the current epidemiology-dominated paradigm through incorporating economic theory and econometric techniques. Dr. Yoo is particularly interested in two quantitative issues regarding influenza vaccination behavior: (i) how individual behavioral patterns respond to external factors such as limited vaccine supply and epidemic levels, and (ii) effects of such behavioral responses on the population-wide benefits of influenza vaccination programs. Trained as a health economist, Dr. Yoo has strong quantitative skills in addition to his background in clinical medicine and public health. The career development part of the K25 grant proposal will enable him to strengthen his quantitative skills in economics (e.g., dynamic modeling) and statistics (e.g., panel data analysis and computer simulation) as well as to gain more knowledge on child influenza vaccination and vaccine distribution/production systems. The specific aims of this method research program are: 1) To develop a dynamic theoretical model for predicting influenza epidemics and individual influenza vaccination receipt and timing, emphasizing potential negative individual incentives incurred by the observations of (i) a lower epidemic level or (ii) a high population flu vaccination coverage level;2) To conduct empirical analyses among Medicare elderly (a) to examine the determinants of flu vaccination receipt and its timing, including vaccine supply delay/shortage, current and prior epidemic levels, mass media reports, travel time cost to a clinic, and reimbursement rates for health care providers, (b) to explore if vaccine shortage exacerbates health disparities in vaccination receipt and its timing (e.g., the later the worse), (c) to examine influenza vaccine effectiveness in reducing flu-related hospitalization and mortality, adjusting for self-selection bias, e.g., the sicker elderly are more likely to be vaccinated;3) To construct computer simulation models for predicting the population-wide benefits of influenza vaccination programs targeting all children and the non-elderly adult population.