Abstract

Background: People who use drugs (PWUD) represent a socially vulnerable population with increased risks for infectious diseases and often demonstrate lower levels of vaccine uptake. Understanding psychological and social determinants of COVID-19 vaccination in this group is essential for designing targeted interventions. This study aimed to evaluate factors associated with unwillingness to receive COVID-19 vaccination among PWUD in Kazakhstan, using the 5C Psychological Antecedents of Vaccination model. Methods: A cross-sectional survey was conducted among PWUD attending addiction treatment facilities. Data were collected through structured questionnaires covering sociodemographic characteristics, health status, and the 5C Psychological Antecedents of Vaccination model. Logistic regression analyses were applied to identify predictors of COVID-19 vaccination uptake and unwillingness to vaccinate. Results: Among respondents, confidence and collective responsibility were inversely associated with unwillingness to vaccinate, while higher levels of complacency significantly increased refusal. Although constraints and calculation were significant in unadjusted models, they lost significance after adjustment, suggesting a secondary role compared with trust and risk perception. Age, gender, income, and somatic comorbidities were not significantly associated with vaccination status. Conclusion: Psychological determinants, particularly confidence, complacency, and collective responsibility, play a decisive role in shaping COVID-19 vaccination behavior among PWUD. These findings emphasize the need for targeted interventions that enhance trust in vaccines and health systems, reduce complacency through tailored risk communication, and highlight prosocial benefits of vaccination. Considering the limited and non-random sample, as well as unmeasured potential predictors, further multi-site studies are warranted to strengthen evidence and inform public health strategies.