Background
Low-level viremia (LLV), defined by the World Health Organization as viral load between 51-999 copies/mL, has been shown to be associated with an increased risk of virological non-suppression and failure among adults on antiretroviral therapy (ART). It is unknown if adolescents living with HIV (ALHIV) and on ART, who are more likely to have poor adherence compared to adults, are more likely to have experienced low-level viremia. There is also limited data factors shaping progression to virological failure among ALHIV on ART. We aimed to assess the prevalence of low-level viremia among ALHIV on ART and associations between LLV and progression to virological failure.
Methods
We analysed viral load data from a longitudinal cohort study of ALHIV (aged 10-19 years at baseline in 2014/2015) captured by the National Health Laboratory Services (NHLS) in South Africa. Using routine viral load data between 2015-2022, we calculated the prevalence of LLV at the first viral load test for all adolescents with results (n=737), then testing which socio-demographic factors were associated with LLV at first test. Among ALHIV who had at least three consecutive viral load tests between 2015-2022, we assessed the relationship between LLV (at the first test) and virological failure (defined as two consecutive viral loads ≥1000 copies/mL) controlling for age, sex and mode of HIV acquisition using logistic regression in RStudio.
Results
A total of 737 ALHIV had at least one viral load result between 2015-2022, amongst whom the prevalence of LLV at first available viral load test increased from 12.4% in 2015 to 18.3% in 2022. Among those with at least one result, older adolescents were more likely to have LLV (OR: 1.09; CI: 1.03, 1.25). Both sex (OR: 0.95; CI: 0.60, 1.51) and mode of HIV acquisition (OR: 0.96; CI:0.52, 1.79) were not significant predictors for LLV. Among 628 ALHIV who had at least three consecutive viral load records during the time period analysed, 13.4% had LLV at the first viral load and 18.6% had progressed to virological failure. ALHIV with LLV were two times (OR: 2.98; CI: 1.64, 6.15) as likely to progress to virological failure compared to those with undetectable viral loads (viral load ≤50 copies/mL).
Conclusions
The prevalence of LLV among ALHIV on ART is high and LLV strongly predicts virological failure. Age also serves as a predictor for LLV. This highlights the need for enhanced adherence support among ALHIV with LLV and not just those with viral non-suppression.
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