Objective To evaluate the cost-effectiveness of different influenza vaccination rates among the elderly population aged 65 years and above in Qingdao city.

Methods A Markov model was constructed to evaluate the cost-effectiveness of different influenza vaccination rates for influenza prevention. The per capita gross domestic product (GDP) of Qingdao city in 2021 was used as the willingness-to-pay threshold for one quality-adjusted life year (QALY). The target population was the elderly aged 65 years and above in Qingdao city. The model time horizon was one year. Three influenza vaccination rates were set at 20%, 40%, and 75%, respectively. Univariate and probabilistic sensitivity analyses were performed to assess the impact of different parameters on the results.

Results Compared with no influenza vaccination, a 20% vaccination rate could reduce the number of influenza infections by 11 942 cases, reduce the total cost by 847 831.97 CNY, and increase the total QALYs by 6 964.09; a 40% vaccination rate could reduce the number of influenza infections by 23 884 cases, reduce the total cost by 1 695 663.95 CNY, and increase the total QALYs by 13 928.19; and a 75% vaccination rate could reduce the number of influenza infections by 44 782 cases, reduce the total cost by 3 179 369.90 CNY, and increase the total QALYs by 26 115.36. Univariate sensitivity analysis showed that the top four parameters affecting the results were the influenza rate in the unvaccinated population, the influenza rate in the vaccinated population, the cost of inpatient treatment, and the cost of outpatient treatment, respectively. Probabilistic sensitivity analysis showed that all three vaccination rates had more than a 90% advantage compared with no vaccination.

Conclusions Compared with no influenza vaccination, increasing the influenza vaccination rate among the elderly population aged 65 years and above in Qingdao city has a high cost-effectiveness advantage.