Efficacy and Safety of Arbidol (Umifenovir) in Adults with Influenza and Other Acute Respiratory Viral Infections: A Systematic Review and Meta-Analysis

Objective: To evaluate the efficacy and safety of umifenovir for the treatment and prophylaxis of influenza and other acute respiratory viral infections (ARVIs), including evidence from Russian-language clinical trials not previously incorporated into international systematic reviews. Methods: PubMed, eLibrary, China National Knowledge Infrastructure, and national archives were searched for randomized controlled trials (RCTs) and prospective or retrospective studies comparing umifenovir with placebo, no antiviral therapy, or oseltamivir. Results: Twenty-three studies were included: 12 therapeutic (n = 5083) and 11 prophylactic (n = 13,663). In RCT subgroups, umifenovir reduced intoxication symptoms (MD: −0.94 days; 95% CI: −1.62 to −0.26) and overall illness duration (MD: −1.17 days; 95% CI: −2.23 to −0.10) but not fever duration (MD: −0.58 days; 95% CI: −1.31 to 0.16). In the overall analysis, umifenovir reduced the risk of complications (RR: 0.39; 95% CI: 0.24–0.62). Prophylaxis reduced laboratory-confirmed influenza (RR: 0.39; 95% CI: 0.28–0.54). Adverse events were infrequent 3.6% (95% CI: 2.4–4.8%) and did not differ significantly from placebo (RR 0.59; 95% CI: 0.34–1.03). Conclusions: Umifenovir was associated with improved clinical outcomes and reduced infection risk, with a favorable safety profile. Inclusion of regionally published evidence expands the available evidence base.