The polyvalent utility of the GeneXpert hardware platform is, however, hitherto largely unexplored despite the widespread deployment of machines. HIV VL testing is currently done in South Africa according to the National HIV Treatment guidelines, which advise measuring HIV VL every six months for the first year of treatment and annually thereafter. HIV VL testing involves collection of a blood sample, transporting it to a centralised laboratory for VL quantification, reporting the result back to the clinic, and calling the patient back. If HIV VL is found to be over 1000 genomes per ml, the patient may not be adherent to the prescribed ART or may have drug-resistant HIV and, now that a failure of virologic suppression has been confirmed, the patient may be asked to give a second blood sample for drug susceptibility testing and may have a counselling visit scheduled, in order to improve the patient's adherence. There is, however, a large amount of discretion at local clinics as to what constitutes virologic failure and patients with increased VL may still receive these interventions, even if below the 1000 genomes per ml threshold. The investigators also intend to perform Xpert HIV-1 VL testing and, compared to patients who receive the standard-of-care of centralised VL testing, evaluate the proportion of patients without virologic suppression who are referred to a follow-up intervention (DST and/or adherence counselling).