The infodemia phenomenon exposed the confrontation scenario of far-right populist politicians against scientific evidence in the treatment and control of Covid-19 through digital social media. Such narratives are marked by political-ideological beliefs and positions placed in antagonisms. This article aims to map and analyze the current brazilian president's arguments about Covid-19 vaccination on Twitter. Using Van Leeuween's legitimation strategies (2007), systematized by Recuero (2019, 2020), we analyzed 19 posts about the subject published in Jair Bolsonaro's official profile to understand his ways of arguing in relation to the Covid-19 vaccine, the way he turns vaccination into a political-ideological dispute and how he makes Twitter a space for confrontation. In our investigation, we observed that the president, based on a populist and neoliberal logic, uses authorization and rationality strategies to build the narrative that the individual has the freedom to choose whether to vaccinate or not