The Relationship between Influenza Vaccine and Hospitalization and Mortality in the Elderly: A Systematic Review and Meta-Analysis

In recent years, various studies have been conducted to investigate the role of influenza vaccine in reducing the risk of hospitalization and death in the elderly. However, the results of these studies are clearly contradictory. Accordingly, the present study aimed to investigate the relationship between receiving the flu vaccine with the risk of hospitalization and mortality in the elderly.

This study was a systematic review and meta-analysis of clinical trial studies published in databases (Web of science, Scopus, PubMed, Cochrane, Science Direct, Google Scholar, and Embase) between the years 1980 and 2020. All analyzes were performed by Stata14 statistical software, and the significance level in this study was considered as 0.05.

In the initial search, 283 articles were retrieved of which, considering the study criteria, finally 9 clinical trial studies were included in the meta-analysis. Based on the results of meta-analysis, the overall odds ratio (OR) of hospitalization for the elderly was equal to 0.65 (95% CI: 0.82 - 0.51; P <0.001); and the overall OR of death was equal to 0.95 (95% CI: 0.92 - 0.97; P <0.001). There was no publication bias in the study of the relationship between receiving the flu vaccine and hospitalization and mortality of the elderly.

Getting the flu vaccine in the elderly can reduce the risk of hospitalization by 35% and the risk of overall death by 5%. Therefore, it may be promising to receive this vaccine as a preventive intervention for elderly deaths and hospitalizations.