[A systematic review and meta-analysis of effectiveness of influenza vaccine among healthcare workers].

Objective

To systematically evaluate the protective effect of influenza vaccine among healthcare workers (HCW).

Methods

Relevant literature from January 1, 2000 to November 4, 2025, was retrieved from China National Knowledge Infrastructure (CNKI), Wanfang Data Knowledge Service Platform, China National Biomedical Literature Service System, National Library of Medicine database, Dutch Medical Abstracts database, and Cochrane Collaboration Library. Two independent researchers screened the literature, extracted data and assessed the quality of the studies, based on predefined inclusion and exclusion criteria. Studies using cohort design and test-negative design were included. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. A meta-analysis was performed using R software version 4.3.3, with vaccine effectiveness (VE) as the effect measure, to calculate the effectiveness of influenza vaccine among HCW.

Results

A total of 24 articles involving 27 studies were included, analyzing the effectiveness of influenza vaccine among 38 855 HCW. Meta-analysis results showed that the VE (95%CI) was 33.26% (14.08%-48.15%) for cohort studies and 36.85% (9.05%-56.15%) for test-negative design studies. No statistically significant difference was observed between the two groups (χ²=0.05, P=0.814); thus data were pooled. The pooled effectiveness of influenza vaccine (95%CI) was 34.11% (18.69%-46.60%). Subgroup analysis revealed that the effectiveness against influenza-like illness (ILI) (95%CI) was 25.97% (1.88%-44.15%), while the effectiveness against laboratory-confirmed influenza cases (95%CI) was 42.68% (21.64%-58.07%). Additionally, sensitivity analysis indicated that the results were stable and not significantly affected by publication bias.

Conclusion

The effectiveness of influenza vaccine among HCW is heterogeneous but generally moderate, particularly more pronounced in laboratory-confirmed cases.