Economic Evaluation of Seasonal Influenza Vaccination in Elderly and Healthcare Workers: A Systematic Review and Meta-Analysis

Background: A number of cost-effectiveness analysis of influenza vaccination have been conducted to estimate value of influenza vaccines in elderly and healthcare workers (HCWs). This study aims to summarize cost-effectiveness evidence by pooling the incremental net benefit (INB) of influenza vaccination. Methods: A systematic review was performed in electronic databases from their inceptions to November 2020. Cost-effectiveness studies reporting quality-adjusted life year (QALY), or life year (LY) of influenza vaccination were included. Stratified meta-analyses by population, perspective, country income-level, and herd-effect were performed to pool INB across studies.   Findings: A total of 17 studies were included. Fifteen studies were conducted in elderly, while two studies were conducted in HCWs. For elderly, four studies reported LY and 11 studies reported QALY. For HCWs, one study reported LY and another study reported QALY. According to pre-specified analyses, studies for elderly in high-income countries without herd effect could be pooled. For societal perspective, pooled INB was $330.54 (313.26, 347.81), while that for healthcare provider/payer perspective was $0.13 (-12,822.0, 12,822.3). The findings were robust across a series of sensitivity analyses. Studies in HCWs indicated that influenza vaccination was cost-effective compared to no vaccination or current practice. Interpretation: Influenza vaccination might be cost-effective for HCWs and elderly under a societal perspective, while there remains limited evidence for healthcare provider/payer perspective. Further evidence from such perspective is warranted. Funding: This study was funded by a grant of Immunization, Vaccine and Biologicals department of the World Health Organization. The authors would like to acknowledge the contributions of the US CDC which provided financial support to the development and publication of this report. Grant number US CDC, WHO IVR (U50CK000431). Declaration of Interest: None to declare.