Resistance to antiviral drug(s)

This code indicates that a patient's viral infection is no longer responding effectively to one or more antiviral medications. This resistance can lead to treatment failure, requiring a change in therapeutic strategy. It signifies a documented or suspected diminished susceptibility of the virus to previously effective antiviral agents.

Use this code when a patient's viral load remains high or clinical symptoms persist despite appropriate antiviral therapy, suggesting the virus has developed resistance. It is also applicable when laboratory testing confirms antiviral resistance, such as genotypic or phenotypic resistance assays. This code should be used as a secondary diagnosis to the underlying viral infection.

• Always sequence the underlying viral infection code first, followed by this resistance code.
• Ensure documentation clearly supports antiviral resistance, either clinically or through laboratory findings.
• Do not use this code for treatment non-compliance or adverse drug reactions; it specifically denotes viral resistance.