ICD-10 Code B97 – Viral agents as the cause of diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B97 – Viral agents as the cause of diseases classified elsewhere
What it is
This code identifies a viral agent documented as the cause of another condition classified elsewhere. Use it when the virus is named, but the primary diagnosis remains the associated disease.
Clinical signs
Clinical features vary; refer to documentation. The record should clearly link a specific viral agent to the condition being treated or evaluated.
When to use this code
Use B97 when the provider states that a virus is the cause of a separate diagnosis, such as a secondary infectious or inflammatory condition. It supports sequencing with the main diagnosis code for the affected body system or disease. Check documentation if the causal relationship is unclear.
Do not use for
Do not use B97 as the principal diagnosis for the illness caused by the virus. Do not assign it when the record does not identify a viral cause or when the condition itself has a more specific code.
Coding tip
Capture the named virus and code the underlying condition first unless documentation says otherwise.