PROJECT SUMMARY: Sarah Nowak, PhD, Research Project Leader (RPL) The World Health Organization (WHO) has identified vaccine hesitancy as one of the top ten threats to global health. Vaccine hesitancy has been associated with beliefs that may be seemingly unrelated to vaccines, including both true conspiracy beliefs. When beliefs become part of the cultural norms of a group they are known as cultural scaffold beliefs; some cultural scaffold beliefs are strongly intertwined with perceptions of disease and vaccines. Nevertheless, most interventions developed to increase vaccine acceptance act on perceptions of either the vaccine-preventable disease (e.g., cautioning about risks) or the vaccine itself (e.g., messages about vaccine safety) without considering the underlying scaffold beliefs. Perhaps not surprisingly, the efficacy of such interventions has been disappointing. Our long-term goal is therefore to develop interventions that act on cultural scaffold beliefs to reduce global vaccine hesitancy. Increasing the voluntary vaccination rate could prevent up to 1.5 million deaths globally each year. In Brazil, President Jair Bolsonaro has endorsed and disseminated misinformation and false conspiracy theories about COVID-19 and its vaccines. Furthermore, Brazil has one of the world’s most successful childhood vaccination programs, making it an excellent case study to examine the relationship between COVID-19 misinformation cultural scaffold beliefs and adoption of vaccine-hesitant beliefs related to childhood vaccination. We will use social media data from Brazil to address our overarching hypothesis that vaccine hesitancy within a community is strongly influenced by prevailing cultural scaffold beliefs in the following three aims: Aim 1: Determine the association between COVID-19 conspiracy beliefs and childhood vaccine hesitancy. Aim 2: Determine how receipt of anti-vaccine versus pro-vaccine information influences decision making in vaccine-uncertain parents. Aim 3: Develop an agent-based modeling tool for studying the joint dynamics of cultural scaffold and vaccine hesitancy beliefs.