This study examines the intersection of disinformation, post-truth dynamics, and the epistemic crisis in Nigeria, with a specific focus on the COVID-19 Infodemic and vaccine misinformation. Utilising a secondary research methodology—analysing academic journals, policy papers, and digital records—the study explores how social media algorithms and emotional contagion facilitate the spread of harmful narratives. The investigation reveals that the proliferation of "fake news" regarding COVID-19 and vaccines destabilised social order, fueled vaccine hesitancy, and widened the knowledge gap between the public and health authorities. Key findings highlight the role of religious and traditional leaders in influencing public perception, as well as the impact of social media "echo chambers" created by proprietary algorithms. The paper concludes that addressing these challenges requires a multi-sectoral approach, including increased government funding for health communication, algorithmic reform by social media firms, and the implementation of robust fact-checking mechanisms.