<p>Moral values and emotions interact to shape attitudes and their strength. While prior research suggests that attitudes associated with moral judgments are more resistant to change, this relationship has primarily been examined using self-reported measures. Moreover, emotions are closely tied to moral judgments, yet their moderating role in the morality-attitude stability relationship remains under explored. Using over 15 million tweets about COVID-19 vaccines from 1.7 million users over a year on X (formerly Twitter), we examine the interaction between moral and emotional associations and stability of attitudes towards COVID-19 vaccines over time. Our findings reveal that emotions shape the effects of moral values in nuanced ways– all emotions except disgust amplify the positive impact of care on stability, sadness diminishes the destabilizing effects of purity and liberty, and happiness does not influence the role of authority or fairness. These findings highlight the complex interplay between morality and emotions in shaping attitude persistence, contributing to a deeper understanding of moralized attitudes in digital discourse. The study also underscores the value of social media as a tool for investigating attitude dynamics beyond traditional self-report measures.</p>