Impact Estimation of Expanded Program on Seasonal Influenza Immunization in Thailand

Abstract

The objective of this study was to estimate the impact of the influenza immunization program on morbidity, mortality and economical benefit in 3 groups, including 1) elderly > 65 years of age with certain chronic conditions, 2) elderly > 65 years of age without certain chronic conditions, and 3) patients with certain chronic conditions < 65 years of age. The certain chronic conditions included cerebrovascular disease, asthma, chronic obstructive pulmonary disease, heart disease, renal failure, diabetic mellitus, and cancer with chemotherapy. The impacts were estimated by using decision tree model as a frame of analyses based on the provider perspective and secondary data were applied. Morbidity, mortality, and related expense between the population with and without the immunization program were compared. The study results revealed that to implement the program on the 3 target groups including 6,100,579-6,323,183 population would need 789-970 million baht per year. The program could decrease 420,817 - 581,563 cases of influenza, 23,566 - 32,568 cases of pneumonia, 2,324 - 3,211 deaths, and could save 628-868 million baht per year on treatment cost. Sensitivity analyses suggested that high impact factors to the economical benefit included influenza incidence, vaccine efficacy, in-patient treatment cost, influenza pneumonia incidence, vaccine cost, and target group. Influenza immunization for patients with the certain chronic conditions was beneficial, while healthy elderly was not.