Influenza disease burden investigation and cost-effectiveness analysis based on system dynamics model

To investigate the economic burden of influenza in Chongqing and evaluate the health economic effects of different influenza vaccination strategies. A sample survey was conducted among confirmed influenza cases in Chongqing from September 2024 to March 2025 to determine incidence profiles, epidemiological characteristics, and economic burden for establishing a system dynamics model of influenza. A total of 1,023 questionnaires were collected, with 1,022 valid responses yielding a response rate of 99.90%. Among valid respondents, the male-to-female ratio was 1:1.05, median (P25-P75) age was 28 (6, 56), and only 30 individuals (2.94%) had received influenza vaccination within four years prior. Total direct medical costs reached 3,184,877 Chinese yuan (CNY), with an average of 3,116.32 CNY and median of 500 CNY per person, while total economic costs amounted to 3,519,954.00 CNY, with a mean of 3,444.182 CNY and median of 600 CNY per person. All economic burden indicators showed statistically significant differences across age groups and chronic disease status ( P < 0.005). Significant variations ( P < 0.005) were observed in average monthly individual household income across groups categorized by direct medical burden, direct non-medical burden, direct economic burden, and total economic burden. However, the indirect economic burden did not demonstrate statistically significant differences among these income groups ( P = 0.229).System dynamics simulations revealed nonlinear cost-effectiveness patterns with threshold effects as vaccination coverage increased from 10% to 100%. Influenza imposes substantial economic burdens on patients, particularly through hospitalization costs. Vulnerable populations include minors, elderly individuals, those with chronic diseases or underlying medical conditions, and low-income groups. Vaccination demonstrates effectiveness as an intervention strategy for influenza prevention and control. Under the assumptions of our model, the cost-effectiveness ratio was most favorable at approximately 50% vaccination coverage.