Conversational Agent Vaccine Promotion RCT

4.1.a.1. Randomization. Study participants will be randomized into one of the four study conditions (ENGAGEMENT x TAILORING) using blocked randomization with randomly permuted block sizes of 2 and 4, by software on the central server referenced when participants first activate the app on their phone. Participants will continue using the app at home, and will be called at 6 months and 12 months to assess outcome measures during a videoconference call with a research assistant. 4.1.a.2. Qualitative Interviews. The investigators will conduct interviews with a sample of participants completing the study (12), as well as with Church and Health Ministry leadership (12) to understand overall acceptance of ECA-ACE and barriers to deployment and use. 4.1.a.3. Qualitative Methods for all Project Focus Groups and Interviews. Videoconference-based focus groups and interviews will be facilitated using a semi-structured interview guide, audio-recorded, and transcribed verbatim by a professional transcription service. The investigators will conduct a thematic analysis of these transcripts guided by the investigators' research questions with the aim of identifying design insights. The investigators will use grounded theory analysis, including constant comparisons, axial and selective coding, and memo writing. Using NVivo 12.5.0 software, two researchers will inductively code transcripts separately, labeling emergent phenomena in the data to arrive at a codebook. Two researchers will then independently apply the codebook to participant transcripts, meeting regularly to discuss discrepancies in the applications of the codes, updates to the codebook, and contradictory data. Sample sizes specified should be adequate to reach thematic saturation relative to the investigators' research questions.