[Cost-effectiveness analysis of quadrivalent influenza vaccination for older adults aged 60 and above in mainland China].

Objective: To evaluate the cost-effectiveness of government fully-funded quadrivalent influenza vaccination (QIV) program for older adults aged 60 and above in mainland China. Methods: Based on decision tree model in the previous research on the cost-effectiveness analysis of TIV immunization, we extended the structure of model and updated the key parameters such as influenza patients' healthcare seeking behavior, vaccine cost, vaccine coverage and vaccine efficacy/effectiveness to estimate influenza-associated outpatient consultations, hospitalizations, respiratory disease excess mortality and quality-adjusted life years (QALY) between the QIV and no vaccination or TIV program. And incremental cost and incremental cost-effectiveness ratio (ICER) were evaluated between the QIV and no vaccination or TIV program from the societal perspective. The time frame of the study is one year. All costs were adjusted to 2019 using the consumer price index. Results: Comparing the fully-funded QIV and no vaccination or TIV for older adults aged 60 and above is separately expected to prevent 45 070 or 2 718 influenza-associated influenza-like illness (ILI) outpatients, 21 451 or 1 294 influenza-associated severe acute respiratory infection (SARI) hospitalizations, 19 346 or 1 167 influenza-associated respiratory excess deaths and avoid 155 234 or 9 363 QALY loss each year. Compared with no vaccination, introducing QIV into National Immunization Program (NIP) is expected to increase the cost of 11.71 billion yuan from the societal perspective. The incremental cost per QALY gained between QIV and no vaccination was 75 325 yuan per QALY, which is higher than willingness-to-pay (WTP) threshold (one-fold gross domestic product per capita is considered as WTP: 70 892 yuan) and means no cost effective. Introducing QIV rather than TIV into NIP will cost 7.98 billion yuan from the societal perspective and the ICER was 852.54 thousand yuan per QALY which is much higher than WTP and means no cost effective as well. The threshold of vaccination cost between QIV and no vaccination or TIV should no more than 113.41 or 6.83 yuan when the two comparators' scenarios above are all cost effective. Conclusion: Under the condition of current vaccine effectiveness and vaccine cost, comparing fully-funded QIV with no or TIV vaccination program is not cost effective for people aged 60 years or older.