Methods
We will conduct a formative mixed-methods study and three sub-trials in Kilimanjaro and Arusha Regions among (1) children aged 0–14 years and their caregivers, (2) adolescents aged 15–19 years and (3) breastfeeding women and their HIV-negative infants. In the formative study, we will collect and analyse data on needs and contents for DATs, including the contents of short message service (SMS) texts and tailored feedback. The results will inform the customization of the DAT to be tested in the sub-trials. In the trials, participants will be randomized in the intervention arm, where the DAT will be implemented or the control arm, where standard care will be followed. Participants in the intervention arm will take their medication from the Wisepill box and receive daily reminder texts and tailored feedback during clinic visits.