Study design and population
We used a cluster-randomized trial design with the intervention and control groups running concurrently. Cluster randomization was chosen for practical reasons and to prevent contamination by patient or nurse preferences. The randomization unit was the HIV care and treatment facility, and the unit of analysis was the patient’s viral level. Concerns that the trial’s ability to detect an effect of VLS would be hampered by lower-than-expected children with high viral loads necessitated a protocol amendment 1 month into the study. We approached 25 health centers to join the study and randomly assigned them to either the Konga intervention group (n = 5) or the control arm (n = 20).