Antiviral Dispensing for Influenza Outpatients Younger Than 65 Years With Comorbidities: A Retrospective Cohort Study

Real-world evidence on antiviral dispensing for influenza outpatients with underlying medical conditions (UMCs) is limited. We characterized dispensing among influenza outpatients aged <65 years with UMCs, comparing commercial and Medicaid coverage.

We used outpatient encounter claims from the US MarketScan Commercial and Medicaid databases during October-April of the 2018-2019 through 2023-2024 influenza seasons and October-December 2024-2025. Eligible encounters included patients aged <65 years with a clinical influenza diagnosis, ≥1 UMC, and ≥12 months of continuous enrollment before diagnosis. Antiviral treatment was defined as dispensing of oseltamivir, peramivir, zanamivir, or baloxavir within 7 days of the encounter. We described demographic, clinical, and care-seeking characteristics and evaluated overall and same-day dispensing by insurance type.

Among 549 424 encounters, 268 463 (48.9%) were commercially insured (median age 19 years [interquartile range, IQR, 8-44]) and 280 961 (51.1%) were Medicaid insured (median age 10 years [IQR 5-18]). Chronic pulmonary disease was the most common UMC (88.0% and 81.8%). Antivirals were dispensed in 54.2% (commercial) and 53.7% (Medicaid) of encounters, almost exclusively oseltamivir. Same-day dispensing occurred in 91.1% of commercial and 81.4% of Medicaid encounters. Overall dispensing was lowest among patients with emergency department encounters or multiple outpatient visits; same-day dispensing was lowest among those with multiple UMCs, emergency department encounters, or multiple visits. Dispensing increased with age in commercial encounters but declined among adults with Medicaid.

About half of higher-risk influenza outpatients received antivirals. Overall dispensing was similar by insurance type, but Medicaid patients and those with multiple UMCs had greater delays.