Overview
Introduction
Antiviral prescribing is a clock and clearance problem, not simply a response to a positive viral test.
Antiviral prescribing is a clock-and-clearance problem, not simply a response to a positive viral test. The safest choice depends on the suspected virus, the stage of illness, the patient’s severity and risk of deterioration, renal function, interacting medicines, pregnancy or lactation, and the treatment access pathway. For a Canadian NP, the first pass is practical: identify the likely virus and site of infection, record the exact symptom or exposure timeline, screen for severe disease and high-risk features, assess kidney function when relevant, reconcile all medicines, and verify the provincial or territorial pathway for COVID-19 treatment. Access criteria and coverage are not identical across Canada. [7,12] Antivirals suppress active replication; they do not replace oxygenation, haemodynamic support, or urgent reassessment. The 2025–26 drifted influenza H3N2 subclade K does not change antiviral choice or dosing, but compatible influenza remains possible in a vaccinated patient. [1,2]