Virological Failure Definition

Threshold Clarification

The International Antiviral Society-USA (IAS-USA) guidelines define virological failure as confirmed HIV RNA >200 copies/mL, not 1000 copies/mL, across their 2016 and 2020 recommendations 1, 2, 3, 4
The 200 copies/mL threshold requires confirmation with a repeat measurement within 4 weeks to exclude laboratory error or transient elevation 1, 2, 5

A virological blip is defined as an isolated increase in HIV RNA to <1000 copies/mL with subsequent return to undetectable levels, and this is not considered virological failure 3, 4
Switching ART based on a single blip is not recommended, as blips rarely progress to true virological failure 3, 4

HIV RNA persistently between 50-200 copies/mL represents a gray zone where data are inconsistent regarding long-term outcomes 1, 2
Patients with persistent viremia in this range should be reassessed for adherence issues, drug interactions, and monitored closely with repeat testing within 4 weeks 1, 2

Treatment should be changed in patients with persistent HIV RNA above 200 copies/mL after confirmation 1, 2
Genotypic resistance testing should be performed at the time of confirmed virological failure, though amplification may not be successful below 500-1000 copies/mL 1, 2, 5
If HIV RNA remains above the limit of quantification by 24 weeks after ART initiation, or if rebound above 50 copies/mL occurs at any time during treatment, repeat testing within 4 weeks is required to assess for impending virological failure 1, 2, 5

Do not confuse a single detectable viral load with virological failure—confirmation is required 1, 2, 3, 4
Do not switch therapy based on isolated blips <1000 copies/mL that return to undetectable levels 3, 4
Do not order resistance testing for viral loads <200 copies/mL, as the test is unlikely to amplify successfully and does not meet the threshold for confirmed failure 1, 2