Context dependent preferences in prestige bias learning about vaccination in rural Namibian pastoralists.

Extensive work in the social sciences suggests that vaccination decisions are subject to incentives, biases, and social learning processes, including prestige bias transmission. High status figures, like doctors and public health officials, can be effective messengers for vaccination information and uptake under certain conditions. In communities where there is significant medical mistrust and less interaction with markets and formal medical systems, prestige bias social learning may operate through different channels. Here, we examine the role of prestige bias on vaccine decisions in two ethnic groups (Himba and Herero) with varying levels of market integration and experiences with formal healthcare systems. Participants completed a ranking task, comparing the influence of four prestigious individuals on vaccine decisions and a survey on medical mistrust. Using Plackett-Luce models, we compare the influence of location, ethnic affiliation, and other covariates on rankings. A multi-level model compared the influence of those within and outside one's ethnic group, as well as specialist (doctor/healer) and generalist (chief/governor) prestige figures. Results indicate changes in the rank of prestigious individuals across the rural-urban gradient. Our results demonstrate significant variability in prestige-biased social learning about vaccine decision making. Medical mistrust did not impact rankings. Contrary to previous work, we find that whether a prestigious individual is locally prominent is more important than their expertise in the relevant domain (health and healing). These findings emphasize the need for more context-specific studies of prestige bias, which can improve our understanding of healthcare decision-making and guide public health messaging across diverse contexts.