Vaccines are an essential public health resource for disease containment and reduction of associated mortality rates. With the emergence of COVID-19, public debates on the themes of vaccines and vaccination processes became important topics on diverse media and social networking platforms. In this article, our objective was to identify and reflect on the emotions evoked in the Brazilian public with respect to the COVID-19 vaccine during 2020 and 2021 on Facebook. To achieve this, we used the Crowdtangle graphical interface to extract complete copies of posts made by public Facebook profiles during this timeframe, from which a random sample of 1,067 posts was selected for analysis. Identification of emotions was performed using the Human-Machine Interaction Network on Emotion (HUMAINE) descriptors as a baseline reference. Emotions were then grouped into categories following Core Affect Model guidelines. Data analysis and interpretation indicated a prevalence of positive emotions such as trust, interest, and hope directed toward vaccines in the Brazilian domestic scenario. Negative emotions such as worry and disapproval were also expressed, albeit in reference to contextual issues (for example, the spread of COVID-19, delays in vaccine access, and the emergence of new variants) and public figures, such as the President of Brazil.