Changes in Antiviral Treatment for Hospitalized Adults with Influenza in U.S. Emergency Departments

This is the authors' abstract. We don't add key points for this paper.

Background Early administration of an antiviral reduces influenza-related complications, and multiple guidelines recommend prompt antiviral treatment for all hospitalized patients with influenza. However, there is limited data on early antiviral treatment within the Emergency Department (ED). Objectives Our epidemiological study assesses temporal trends in the initiation of antiviral treatment for adults hospitalized with influenza in the ED and identifies factors associated with nonadherence. Methods This retrospective cohort study examined antiviral treatment patterns among adults hospitalized with influenza in a U.S. ED from 2016 to 2025, using Epic Cosmos. Patients with ICD-10–coded or laboratory-confirmed influenza A/B were included. The primary outcome was the proportion of hospitalized patients who received oseltamivir, peramivir, baloxavir, or zanamivir in the ED. Results Of the 483,459 hospitalized ED patients with influenza, 416,982 (86.25%) received an antiviral in the ED. Antiviral treatment ranged from 72.7% in 2021 to 91.08% in 2020, rebounding to 85.11% in 2025. Differences in demographics between treated and untreated patients were observed across age, ethnicity, race, and spoken language. The likelihood of antiviral therapy was lower in the South (OR 0.95; 95% CI 0.93-0.97) and West (OR 0.78; 95% CI 0.76-0.80) compared to the Northeast of the US. The rate of antiviral treatment was moderately correlated with the national rate of influenza positivity in the ED (Pearson correlation 0.59). Conclusion Although prompt administration of an antiviral for hospitalized patients reduces influenza-related complications, antiviral administration is not universal in the ED. Our study highlights a critical gap that requires urgent implementation of mitigation strategies.