CoronaVac, developed in Brazil by the Butantan Institute in partnership with Sinovac, remained amid the political disputes that permeated the way our country faced the COVID-19 pandemic. In order to map and understand, in a limited period, the conversations surrounding the effectiveness of the said immunizer on the social networking site Twitter, the investigation made use of the analysis of social networks. To visualize the data, semantic maps were created that helped to identify what was being said about the effectiveness of CoronaVac, allowing the content analysis of some of the main tweets and the recognition of the most active profiles. The results point to the fact that, for the most part, network users are not against vaccination, but often question the effectiveness of the vaccine, illustrating, to some extent, the impact of the politicization of the immunizer