In this article, we aim to identify and categorize the voices that guided the debate on vaccines in the Brazilian digital public sphere in the first two years of the COVID-19 pandemic, a context in which vaccination gained relevance, as it consolidated itself as the main alternative to the control of the global health crisis. To this end, (i) a total of 3,878,408 valid posts related to the theme of vaccines made in Portuguese were collected by open profiles on Instagram and public pages on Facebook, between January 1, 2020, and December 31, 2021; (ii) the 500 social actors from each network who received the most comments on their posts were distributed into macro-categories, with the results pointing to a debate predominantly guided by lay voices, in which agents linked to journalistic activity, politics and public administration stood out. Celebrities and entertainment vehicles also stood out, helping to amplify the debate on vaccines. We highlight the fact that research institutions and scientific disseminators had little presence as mediators of the debate on the topic in the scope of our study.