ABSTRACT
The COVID-19 pandemic created the need for universal vaccination. This study aimed to compare university students' (pre-service teachers) conceptions who had already learned the immune system and vaccination topics in the "Human Biology and Health (HBH)” curricular unit with those who had not yet taken part in it. It also intended to verify the influence of secondary school background, perception of one's own health, feeling at risk for COVID-19 and their own experience with it and scientific knowledge related to SARS-CoV-2 vaccination. It was a cross-sectional study with a mixed methodology for data analysis. A questionnaire was applied online to a sample of 102 university students. Results show that students who had already taken the subject on the immune system and vaccination had more acceptable conceptions about the vaccine and wanted to be vaccinated but not in the initial moment of the national vaccination process. The fear of adverse reactions seemed to be the major hesitancy factor. Furthermore, students' argumentation showed that their conceptions progressed towards more socio-scientific reasoning. © 2022 by the authors.