Influenza Antiviral Prescriptions in the US Inpatient and Outpatient Settings During the 2015-2022 Influenza Seasons

The antiviral drug prescription landscape has changed as new antivirals for influenza treatment have been approved. Understanding this landscape is important to assess potential under- and mis-utilization and to address gaps in care. This study characterizes patterns in influenza antiviral use in US healthcare settings using a large claims database.

We included prescriptions of four antivirals: oseltamivir, baloxavir, peramivir, and zanamivir in US healthcare settings between September 2016 and August 2023, using Komodo Health Database. We estimated the percentage of antiviral prescriptions associated with respiratory disease diagnoses, including influenza, COVID-19, and other respiratory conditions, and the percentage prescribed to patients at high risk of influenza complications. We used multinomial logistic regression to assess the association between patient and prescriber characteristics and the choice of antiviral.

Between 865,885 and 3,092,822 influenza antiviral prescriptions were filled annually during the 2016-2017 through 2022-2023 influenza seasons among US insured individuals. Oseltamivir was the most prevalent antiviral type. Baloxavir use remained low, accounting for 1.8%-9.2% of total prescriptions since its 2018 approval. Between 55.6% and 75.4% of prescriptions had an associated influenza diagnosis, with the lowest proportion observed during the 2020-2021 season. Between 2.59% and 5.35% of antivirals were prescribed to high-risk patients. Influenza diagnosis and patient age were associated with prescribing baloxavir rather than oseltamivir.

Among US insured individuals, oseltamivir remained the most prescribed antiviral during the 2016-2017 through 2022-2023 seasons, a pattern consistent with its broader FDA-approved indication across age groups and care settings relative to baloxavir, peramivir, and zanamivir.