Hospitalized adults with flu missed antiviral treatment in emergency departments (EDs), with the treatment rate still below pre-pandemic levels in 2025. The study found that about 14% of hospitalized adults who arrived at US EDs over 10 years did not receive antiviral treatment there, despite guidelines recommending immediate therapy for all hospitalized patients.
Researchers reviewed electronic health record data for 483,459 hospitalized adults with influenza who presented to EDs during 2016-2025. Antivirals were started in the ED for 86.25% of patients, and nearly all treated patients, 98.99%, received oseltamivir.
Flu Miss Antiviral Treatment Rates Shifted After 2020
The treatment rate stayed between 85.14% and 91.08% during 2016-2020. It reached 91% in 2020, then fell to 72.70% in 2021. The rate rose gradually afterward, reaching 85.11% in 2025. The source describes 85%-91% as the pre-pandemic range and says the 2025 rate was at its lower end.
The researchers used Epic Cosmos, an electronic health record database, for a retrospective cohort study. They identified influenza through diagnostic codes or laboratory results confirming influenza A or B. The team assessed ED antiviral treatment and examined demographic and clinical differences between treated and untreated patients, as well as changes over time.
Most people in the cohort were older than 50 years, accounting for 85.35%. Approximately 2.55% died. The study reported differences in treatment odds by age and region. Compared with adults aged 18-30 years, adults aged 40-50 years had higher odds of receiving antiviral therapy (odds ratio [OR], 1.23; 95% CI, 1.17-1.29). Adults aged 78-85 years also had higher odds (OR, 1.54; 95% CI, 1.48-1.61).
Patients hospitalized in the South had lower odds of receiving treatment than patients in the Northeast (OR, 0.95; 95% CI, 0.93-0.97). The odds were also lower in the West (OR, 0.78; 95% CI, 0.76-0.80). Treatment rates were moderately correlated with the proportion of hospitalized patients in the ED who had influenza, with a Pearson correlation coefficient of 0.59.
Study Limits Its Conclusions
The authors wrote that antiviral treatment dropped significantly during the COVID-19 pandemic and had not returned to pre-pandemic levels. They also pointed to increased ED boarding and called for urgent interventions to boost antiviral initiation in the ED for hospitalized patients with influenza.
The study could not establish that any factor caused treatment differences because it was descriptive. Epic Cosmos data lacked information on comorbidities and illness severity, so researchers could not perform risk-adjusted analyses. The database includes health systems on the Epic platform, which may limit how broadly the findings apply. Diagnostic coding could also have missed patients with incomplete records or skewed the cohort toward more severe disease.
The study was led by Kevin G. Buell, MBBS, MS, of Rush University Medical Center in Chicago. It appeared online on September 26, 2026, in The Journal of Emergency Medicine. No specific funding was reported, and the authors reported no conflicts of interest.
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Researchers said the observed decline had not fully reversed by 2025 and called for efforts to increase ED antiviral initiation among hospitalized patients.
The study coverage reports the findings, methods and limitations.
