The objective of this study is to assess the use of and satisfaction with the ECA intervention over a 12-month period, its ability to increase SARS-CoV-2 and influenza vaccination in the BMATP community, and the comparative effectiveness of proactive engagement strategies and cultural tailoring on these factors. The Investigators will assess app use and satisfaction among these participants, along with self-reported vaccination attitudes and behavior, at 6 months and 12 months. During this time the investigators will conduct a 2x2 factorial RCT (with the individual the unit of random assignment and measurement) to assess the impact of two app design features on engagement and outcomes: (1) the investigators will manipulate engagement mechanisms (ENGAGEMENT), including reminder notifications and trust-building dialogue by the ECA and, (2) independently manipulate cultural tailoring of vaccination promotion counseling language used by the agent (TAILORING) to either adaptive religiosity (tailored) or secular (non-tailored). The investigators' primary hypotheses are that participants with have significantly greater vaccination completion rates in the high engagement and tailored conditions at 6 months (H1) and 12 months (H2) compared to other conditions. The investigators' secondary hypotheses are that participants will use the app more, be more satisfied with the ECA, be more advanced in their stage of change, and have greater knowledge, self-efficacy, and decisional-balance from baseline to 6 and 12 months, in the high engagement and tailored conditions. In addition to the RCT participants, all members of the 12 participating BMATP churches will be invited to use the app (via snowball recruitment), to increase the utility of the social networking functions of the app by having as many users as possible.