Background The recent introduction of COVID-19 certificates in several countries, including the introduction of a European Green Pass, has been met with protests and concerns by a fraction of the population. In Italy, the Green Pass has been used as a nudging measure to incentivize vaccinations, since unvaccinated people are not allowed to enter restaurants and bars, museums, or stadiums. Objective This study aims to understand and describe the concerns of anti-green pass individuals in Italy, the main arguments of discussion, and their characterization. Methods We collected data from Telegram chats and analysed with a mixed-methods approach the arguments and the concerns that were raised by the users. Results Most individuals opposing the green pass share anti-vaccine views, but that doubts and concerns about vaccines are not often among the arguments raised to oppose the green pass. Instead, the discussion revolves around legal aspects and the definition of personal freedom. Further, we explain the nature of the dichotomy and similarity between anti-vaccine and anti-green pass discourse, and we discuss the ethical ramifications of our research, focusing on the use of Telegram chats as social listening tool for public health. Conclusion A large fraction of anti-green pass individuals share anti-vaccine views. We suggest public health and political institutions to provide a legal explanation and a context for the use of the green pass, as well as to continue focusing on vaccine communication to inform hesitant individuals. Further work is needed to define a consensual ethical framework for social listening for public health.