This thesis aims to analyse the presence of post-truth characteristics in the public sphere, using the case study of the highly debated COVID-19 vaccines in Europe. Since 2016, the concept of post-truth has received increased attention in academia, particularly around the intense polarization of issues such as partisan voting, climate change, and vaccination. While prior studies have focused significantly on the impacts and emergence conditions of the post-truth phenomenon, empirical studies on the prevalence of post-truth in everyday public activities have yet to be written. In response, this thesis conceptualises post-truth into five characteristics that are described in the existing literature: (i) disagreement about fact, (ii) personal experience and emotion, (iii) neglect of fact, (iv) truth-seeking, and (v) discredit of and distrust in experts. Based on these characteristics, this thesis qualitatively analyses the content of the comments on the European Commission’s Facebook posts concerning the COVID-19 vaccine. Descriptive analysis of 362 user-generated comments shows that groups with varying attitudes toward vaccination display most of the post-truth characteristics described in the existing literature. The results suggest that the group of people who are influenced by the post-truth culture is wider than anticipated. Furthermore, this thesis alters prior understandings of post-truth culture by showing that the opponents of vaccines do not display strong emotions or use personal experiences when discussing vaccination with the others. Public health authorities therefore might take these results into consideration for future vaccination campaigns. Lastly, this study posits some associations between post-truth characteristics and calls for further qualitative research on the matter.