Background: This study assessed the perceptions and attitudes of the Brazilian adult population about COVID-19 vaccines, seeking to identify which factors are associated with vaccine hesitancy and lack of trust in vaccines, in order to support individual or collective strategies for welcoming and guidance. Methods: This is a national survey using a self-report web instrument in a representative sample of the Brazilian adult population (N=1700). The survey included sociodemographic and quality of life (QoL) questions, general information on COVID-19, and a vaccine-specific questionnaire. Results: The vast majority of our sample expressed favourable opinions regarding COVID-19 vaccination, but there was also a small fraction (2.2%) of respondents who are hesitant about COVID-19 vaccination. Most of them were males within age range of 30 to 59 years and reported that their reasons for vaccine hesitation are mainly due to uncertainty about safety (57.9%) and efficacy (36.8%) of vaccines, followed by concern with how they were developed, that is, the issue of timing and the adoption of a new development technology (28.9%). Further, while the impact of groups and peers on those who hesitate to vaccinate was not clear, their perception of a low risk of contracting the disease is evident. Conclusions: The uncertainty about the safety and efficacy of vaccines, the issue of timing and the adoption of a new development technology and the effect of these perceptions on the vaccine COVID-19 acceptance suggests the need to develop targeted strategies to increase effective communication about the risks and benefits of COVID-19 vaccines.