At times of crisis, access to information takes on special importance, and in the Internet age of constant connectedness, this is truer than ever. Over the course of the pandemic, the huge public demand for constantly updated health information has been met with a massive response from official and scientific sources, as well as from the mainstream media. However, it has also generated a vast stream of user-generated digital postings. Such phenomena are often regarded as unhelpful or even dangerous since they unwittingly spread misinformation or make it easier for potentially harmful disinformation to circulate. However, little is known about the dynamics of such forums or how scientific issues are represented there. To address this knowledge gap, this chapter uses a corpus-assisted discourse approach to examine how ¿expert¿ knowledge and other sources of authority are represented and contested in a corpus of 10,880 reader comments responding to Mail Online articles on the development of the COVID-19 vaccine in February¿July 2020. The results show how ¿expert¿ knowledge is increasingly problematized and politicized, while other strategies are used to claim authority. The implications of these findings are discussed in the context of sociological theories, and some tentative solutions are proposed.