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Page 12 of 39 Guideline

If the VL is > 50 copies/mL at any stage, then this should be
If VL > 100 000 copies/mL,
Baseline an indication for urgent action: The patient should receive
then RPV is contraindicated
counselling and interventions should be implemented to
improve adherence. A repeat measurement of VL should
If not virally suppressed, then be done in 2–3 months.
3 months then should have
minimum > 2 log decrease;
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provide adherence counselling
Interpreting viral load results
VL > 50 copies/mL Virological criteria for treatment success
6 months
Treatment success is defined as a decline in VL to
VL < 50 copies/mL < 50 copies/mL within 6 months of commencing ART, and
VL > 50 copies/mL Adherence counselling sustained thereafter.
12 months
Repeat VL in 2–3 months
VL < 50 copies/mL Virological criteria for treatment failure
Every VL > 50 copies/mL Treatment failure is defined as a confirmed VL > 50 copies/mL
6–12 months on two consecutive measurements taken 2–3 months apart:
The decision to alter ART should therefore be based on the
VL < 50 copies/mL
results of repeat testing after 2–3 months, following intensive
RPV, rilpivirine; VL, viral load. adherence counselling. Although previous guidelines used a
FIGURE 1: Timing of viral load monitoring of the patient starting antiretroviral threshold of 1000 copies/mL to define virological failure, there is now
therapy. For patients with a viral load > 50 copies/mL on two consecutive
occasions, refer to the text. good evidence that a VL > 50 copies/mL is robustly associated with
subsequent virological failure, although this has not been
alone, have been shown to result in better patient established. 53,54 Sustained viral replication, even at these low
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outcomes. If the VL is undetectable, then the virus cannot levels, can lead to the accumulation of resistance mutations
mutate and develop resistance. A sustained VL < 50 (although this has not yet been definitively established in the
copies/mL is associated with the most durable benefit. case of DTG).
A suppressed VL also prevents the transmission of HIV
to contacts. Viral blips
Isolated detectable HIV VLs < 1000 copies/mL, followed by
Timing of viral load monitoring in the patient an undetectable VL, are termed ‘viral blips’ and alone are not
starting antiretroviral therapy (Figure 1) a reason to change the ART regimen.
We recommend a baseline VL for the following reasons: • Viral blips can be caused by immune activation (such as
1. The 3-month VL can then be compared with the baseline from an acute infection), variability in the laboratory
VL to detect > 2 log drop, and if this has not occurred, testing thresholds or intermittent poor adherence.
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then it allows for early adherence intervention. Provided that they are infrequent, and the VL returns to
2. It may guide NNRTI selection (RPV should not be used if being undetectable at the next measurement, they are not
VL > 100 000 copies/mL). regarded as consequential.
3. It confirms the diagnosis of HIV (antibody tests may very
rarely give a false-positive result). Reasons for a high viral load
A high VL can be attributed to one or more of these three
A 3-month VL is desirable to detect adherence problems early factors:
before resistance develops. A subset of patients who start • inadequate patient adherence (most commonly)
ART with a very high VL may not be fully suppressed at 3 • resistance to the prescribed ART – including both acquired
months despite 100% adherence, but such patients would and transmitted drug resistance
have had a > 2 log drop in VL from baseline if adherence is • inadequate ART drug levels as a result of altered
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optimal and there is no resistance. Therefore, the 3-month pharmacokinetics, such as absorption difficulties, or
result should be interpreted in relation to the baseline VL. drug–drug interactions.
All patients who have a detectable VL at 3 months should
receive additional adherence interventions. In general, a These explanations are not mutually exclusive. For instance,
patient’s VL declines fastest on InSTI-based regimens. inadequate patient adherence frequently leads to the
development of resistance in patients on a non-DTG-
If the 3-month VL is undetectable, then VL monitoring is containing regimen.
recommended at 6 months and every 6 months thereafter.
In patients who have an undetectable VL for more than Transmitted drug resistance is currently increasing in the
12 months, and who demonstrate reliable adherence and region. Such drug resistance is most frequently associated
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follow-up, it may be acceptable to reduce the frequency of VL with the NNRTI class, as the signature K103N mutation has
monitoring to 12 monthly. little effect on viral fitness and can therefore persist in the

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