Infodemics on Youtube: Reliability of Content and Echo Chambers on COVID-19

Social media radically changed how information is consumed and reported. Moreover, social networks elicited a disintermediated access to an unprecedented amount of content. The world health organization (WHO) coined the term infodemics to identify the information overabundance during an epidemic. Indeed, the spread of inaccurate and misleading information may alter behaviors and complicate crisis management and health responses. This paper addresses information diffusion during the COVID-19 pandemic period with a massive data analysis on YouTube. First, we analyze more than 2M users' engagement in 13000 videos released by 68 different YouTube channels, with different political bias and fact-checking indexes. We then investigate the relationship between each user's political preference and her/his consumption of questionable/reliable information. Our results, quantified using information theory measures, provide evidence for the existence of echo chambers across two dimensions represented by the political bias and by the trustworthiness of information channels. Finally, we observe that the echo chamber structure cannot be reproduced after properly randomizing the users' interaction patterns.