Objectives: This study aimed to identify factors influencing COVID-19 vaccination decisions and reasons for vaccine refusal among young Poles – a population with the lowest uptake in the country. Material and Methods: A nationwide cross-sectional study was conducted using the computerassisted personal interview method on a representative sample of 1560 individuals aged 15–39 years. The multivariate logistic regression model was used to analyze the relationship between selected factors and COVID-19 vaccination status. Results: The likelihood of vaccination was significantly higher among women (odds ratio [OR] = 1.64), individuals aged 25–39 years (OR = 2.47), those with higher education (OR = 4.84), married (OR = 2.18), parents (OR = 2.35) and deeply religious respondents (OR = 4.97). The strongest predictor was fear of COVID-19 infection (OR = 28.14). Among vaccine-hesitant individuals, the most common concerns were vaccine safety (40%) and efficacy (35%). Others perceived COVID-19 as a mild illness (27%), believed prior infection provided sufficient immunity (22%), or preferred natural methods (14%). Vaccination status correlated with attitudes toward vaccines and the pandemic. The strongest positive correlations were with beliefs that vaccination protects others (r_s = 0.59), COVID-19 vaccines are a medical success (r_s = 0.51), and that experts promoting vaccines are credible (r_s = 0.45). Negative correlations were linked to misinformation, such as claims about genetic effects, unethical experimentation, or dangerous ingredients. The reasons for refusing the COVID-19 vaccine cluster into 2 groups: modifiable and non-modifiable. This division assumes that it is possible to intervene to modify some factors, while others are beyond our control. Conclusions: Vaccine hesitancy is shaped not only by lack of knowledge but also by mistrust and social polarization. Therefore, public health strategies should combine educational efforts with communication delivered through trusted channels. Otherwise, polarization may persist – with only part of the hesitant group open to change. Int J Occup Med Environ Health. 2025;38(4):378–390