One potential barrier to internalizing and acting on new health information is whether we are able to hear it in private and ask questions of a trusted messenger. Building on early lessons of providing “health ambassadors” with skills to address individuals’ concerns about the Covid-19 vaccine through brief but meaningful interactions, this research collaborative will work in Côte d’Ivoire, Senegal, Malawi, and Zimbabwe. In each country, this multinational, multidisciplinary collaborative will partner with health authorities to recruit and train ordinary citizens (college students and local community representatives) to serve as health ambassadors using a replicable protocol. The health ambassadors will then proactively engage individuals around vaccine risks and benefits face-to-face in an effort to increase public fluency and confidence in reliable scientific information about Covid-19 and Covid-19 vaccine uptake to ultimately increase vaccination rates. Health ambassadors will offer a direct and private opportunity to discuss vaccination concerns. A multisite randomized control trial will test the nine-month intervention, with the aim of generating generalizable insights with the potential to scale. The ambassador training protocol will be developed in a formative, qualitative phase of the study, and the RCT will roll out alongside vaccination campaigns in urban and rural areas. The study will help health authorities to define a scalable strategy for increasing the speed of public uptake of urgent health measures.