Vaccine acceptance and refusal in Western and Central and Eastern European countries: An analysis based on the European Social Survey data from 23 countries, using a classification and regression tree

This study aims to explore the socio-political and demographic determinants of COVID-19 vaccine acceptance and refusal across Western and Central and Eastern European (CEE) countries. While most existing studies treat vaccine hesitancy as a universal phenomenon, our analysis emphasises the role of national and regional contexts. Using data from the 11th round of the European Social Survey (2023-2024), covering 23 European countries and 39,184 respondents, we applied a Classification and Regression Tree model to identify key predictors of vaccination status. The dependent variable was defined as receiving at least one dose of a COVID-19 vaccine approved by national regulatory authorities. Independent variables included institutional and social trust, political attitudes, voting behaviour, attitudes toward minorities, and socio-demographics. The Classification and Regression Tree model enabled non-parametric analysis of complex and nonlinear relationships and allowed segmentation of respondents based on context-specific predictors. Our findings demonstrate significant regional differences. In Western Europe, vaccine acceptance was strongly associated with voting for non-populist parties and with high institutional trust, suggesting that vaccination is perceived as not only a public health measure but also a civic responsibility. In contrast, in CEE countries, vaccine acceptance was primarily shaped by age and education level, with younger and less educated individuals showing greater refusal. Institutional trust remained a key predictor in both regions. The model achieved an overall classification accuracy of 85.3 %. We argue that the difference between Western Europe and CEE is related to different political circumstances during the pandemic. In Western Europe, populist parties critical of restrictions and vaccination programs were often in opposition. In CEE countries, however, populist parties were mostly in power and managed the health crisis (by introducing restrictions and organizing mass vaccination programs).