Study Confirms Benefits of Early Administration of Oseltamivir for Hospitalized Patients With Influenza

For patients with influenza, does early administration of oseltamivir on day 1 of hospitalization improve outcomes?

In patients with influenza, initiation of oseltamivir on the day of hospital admission reduced the risk of progression of pulmonary disease. The study shows that despite recommendations, many patients in the hospital did not receive oseltamivir on day 1. (Level of Evidence = 2b)

Guidelines recommend the initiation of oseltamivir as soon as possible for patients hospitalized with suspected or laboratory-confirmed influenza. The study was conducted during the 2022–2023 influenza season in 24 hospitals in the United States and examined the clinical benefit of early administration of oseltamivir compared with later initiation or no treatment. The study cohort included hospitalized patients who tested positive for influenza. The authors excluded anyone who was coinfected with SARS-CoV-2 or respiratory syncytial virus, had received treatment other than oseltamivir for influenza, or was discharged on the day of admission. Participants were classified into an early treatment group (ie, patients who were given oseltamivir on day of admission [n = 415]) or a late treatment group (ie, patients who received no treatment [n = 124] or those who received oseltamivir later in the hospitalization [n = 301]). Overall, 78% in the late treatment group received oseltamivir 1 day after admission. The primary outcome was peak pulmonary disease severity during hospitalization, classified by a 5-level scale (1 = no oxygen support, 3 = high flow nasal cannula or noninvasive ventilation, 5 = death). In the early treatment group, patients were older and had higher baseline pulmonary disease severity. Median time from symptom onset to hospital admission was 3 days for the entire cohort. Results were adjusted for baseline disease severity, age, sex, site, and influenza vaccination status. Compared with late treatment, early treatment led to more patients without progression of pulmonary disease severity (8% vs 2%; P < .001), and fewer patients progressing one severity level higher (11% vs 21%; P < .001) or two levels higher (3% vs 7%; P = .027) than baseline. Early treatment patients also had shorter hospital lengths of stay, fewer admissions to the intensive care unit, decreased need for vasopressor use or kidney replacement therapy, and reduced in-hospital mortality.

Study Design: Cohort (prospective)

Funding Source: Government

Setting: Inpatient (any location)

Reference: Lewis NM, Harker EJ, Grant LB, et al.; Investigating Respiratory Viruses in the Acutely Ill (IVY) Network. Benefit of early oseltamivir therapy for adults hospitalized with influenza A: an observational study. Clin Infect Dis. 2025;81(1):190-197.