Data collection
PROMISE-EPI staff members, after having received training in qualitative data collection, contacted the PROMISE-EPI participants and HCP. They conducted face to face individual interviews and focus group discussions based on a semi-structured guide, lasting about 1 h each, between December 2021 and September 2022 in the PROMISE-EPI study rooms.PROMISE-EPI participants received compensation for travel to the study site and for their time (100Kwatcha = 5 USD).Interviews were conducted in one of the 3 main languages in Lusaka, Bemba, Nyanja or English and were audio recorded. Simultaneously translation in English was done when necessary and transcribed by the interviewer, keeping the anonymity of the interviewee by using PROMISE-EPI ID numbers (or a dedicated number for PROMISE-EPI staff and HCP).Participants were asked about facilitators and barriers to lamivudine adherence, with respect to maternal antiretroviral (ARV) adherence and were asked to compare their experience between 3 drugs and single drug prophylaxis.Challenges encountered by the interviewers were identified through a review of the initial transcripts by the social science researcher (RK) and discussed with the study team members. The social science researcher then participated in a sample of focus group of discussions to provide feedback on techniques. A meeting of the study team, conducted after reviewing ten transcribed interviews, determined the approximate number of additional interviews expected to reach saturation.