ICD-10 Code J09.X – Influenza due to identified novel influenza A virus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J09.X – Influenza due to identified novel influenza A virus
What it is
This code identifies influenza caused by a novel influenza A virus that has been specifically identified. Use it when documentation names a novel strain rather than seasonal influenza.
Clinical signs
Clinical features vary; refer to documentation. Influenza commonly presents with acute fever, cough, sore throat, myalgias, headache, and fatigue, but coding depends on the documented novel influenza A diagnosis.
When to use this code
Use J09.X when the provider documents influenza due to an identified novel influenza A virus, such as a confirmed novel strain. It applies when the record clearly distinguishes this from routine seasonal influenza. If the chart only says “influenza” or “flu,” check documentation before assigning this code.
Do not use for
Do not use this code for seasonal influenza without documentation of a novel influenza A virus. Do not apply it when the organism is unspecified or when another respiratory infection is documented instead.
Coding tip
Code the novel strain only when the diagnosis is explicitly documented; otherwise, query the provider.