Objective  To explore the impact of influenza virus co-infection on prognosis of patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Methods  We retrieved studies relevant to outcomes of patients with mono-/co-infection of SARS-CoV-2/influenza viruses published from January 2020 through May 2023 through searching Web of Science, PubMed, Scopus, Embase, the Cochrane Library, and China National Knowledge Infrastructure and with supplementation of literature tracing. R 4.2.1 statistical software was used to perform meta-analysis.

Results  Totally 24 English articles were included in the analysis, which involved 26 610 patients (20 625 SARS-CoV-2 mono-infections, 3 806 mono-influenza virus infections, and 2 179 co-infections of SARS-CoV-2 and influenza virus). The results of meta-analysis showed that the patients with co-infection of SARS-CoV-2 and influenza virus were at increased risk of admission to intensive care unit (odds ratio OR = 2.13, 95% confidence interval95%CI: 1.15 – 3.94), having mechanical ventilation support (OR = 5.02, 95%CI: 2.38 – 10.59), and mortality ( OR = 4.84, 95%CI: 2.21 – 10.61) compared to the patients with mono-influenza virus infection. No publication bias was observed and the analysis results were relatively stable based on publication bias test and sensitivity analysis on the included literatures.

Conclusion  The co-infection of SARS-CoV-2 and influenza virus may result in severe outcomes and affect the prognosis of the patients with the co-infection.