Whose voice matters? Authority and influence in the Italian Twitter debates on Covid-19

The Covid-19 pandemic intensified public discourse on social media, with Twitter becoming a key platform for information exchange. In such environments, authorities—influential figures from various domains—play a crucial role in shaping public opinion, having the power to influence offline behaviors both individually and collectively. In this work, we study the role of pro-vaccine and anti-vaccine authorities within the Italian Twitter debate on Covid-19 in five contextually relevant temporal windows corresponding to different pandemic phases. Analyzing a dataset of over ∼50M tweets, we identify central actors and quantify both their impact and their influence on users’ opinions. Our results suggest that while anti-vax authorities were able to gain more consensus during the vaccination phases, pro-vax authorities became more influential in the latter stage of the vaccination campaign.