In the wake of the pandemic, the greatest obstacle to COVID-19 vaccination in the Caribbean is vaccine acceptance and uptake rather than supply. Social media surveys were conducted in three Caribbean countries to better understand the socio-behavioral drivers of vaccine acceptance and uptake to address ongoing vaccination challenges to prevent morbidity and mortality. Behavioral science made critical contributions to global COVID-19 vaccination campaigns. We wanted to understand vaccine intentions, behavioral biases and barriers limiting vaccine uptake to better target vaccination efforts and inform health communication campaigns. Surveys were administered via Facebook messenger chatbot, with data drawn from a non-probability sample of both vaccinated and unvaccinated respondents. Surveys were conducted in April-May 2022, with respondents from Belize (n=2,657), Jamaica (n=4,096), and Haiti (n=10,419). We focused on the 'movable middle', i.e., people who are still undecided about whether they wanted the COVID-19 vaccine. Further, surveys tested the impact of different behaviorally informed messages on vaccine intention. Each country presented unique vaccination uptake challenges which required specific interventions or outreach strategies to change vaccination attitudes and behaviors. The responses of the movable middle provide insights into how this group could be targeted for improving uptake. Knowledge of this group can aid in targeting messaging, selection of trusted messengers and channels.