REPLICATION MATERIAL to Trust in Science, Knowledge and Risk Perception as Predictors of COVID-19 Vaccination: Application of an Extended Theory of Planned Behavior Model in Hungary (Kopasz et al. 2026, BMC Public Health)

Kopasz, M., Papp, Zs., Zsigmond Cs., Husz, I. (2026) Trust in Science, Knowledge and Risk Perception as Predictors of COVID-19 Vaccination: Application of an Extended Theory of Planned Behavior Model in Hungary. BMC Public HealthAs with COVID-19, where vaccine uptake was a primary way to contain the pandemic, vaccination could be a crucial factor in similar health emergencies in the future. Numerous studies focus on the causes of vaccine hesitancy in national and comparative contexts. Given the huge variation in vaccine uptake across countries, it is essential to look at the determinants of vaccine uptake in as many contexts as possible. This allows for a better understanding of vaccine hesitancy and, hence, creates opportunities for a more effective and safer management of pandemics.Our study investigates the determinants of COVID-19 vaccine acceptance, with a special focus on trust in science. A number of works have shown the importance of some type of trust in vaccination decisions, including trust in government (e.g. Han et al. 2023), in the health system (e.g. Rozek et al. 2021), or confidence in the vaccine (Jennings et al. 2021). Despite its apparent importance in the context of the pandemic, trust in science specifically has only been investigated by a small number of studies (see Sapienza and Falcone 2023). With very few exceptions (e.g. Seddig et al. 2022; Barattucci et al. 2023), these studies did not rely on any established theoretical framework, and examined the direct effect of trust on vaccine acceptance. We contribute to this literature by using the Theory of Planned Behavior (TPB; Ajzen 1991) to explore the role of trust in science in COVID-19 vaccination. While the TPB originally predicts the intention to perform a behavior (i.e. intention to get vaccinated), it is also applicable to predict actual behavior (i.e. vaccine acceptance) (Sheeran 2002; Ali et al. 2023). In our modified TPB model, COVID-19 vaccine acceptance is the product of three factors: (1) attitudes towards vaccination, (2) subjective norms (i.e. an individual’s perceptions of what significant others think about vaccination, and (3) perceived behavioral control (i.e. perceived difficulty of performing the behavior). In this study, we extend the TPB model with further predictors of attitudes toward vaccination: trust in science, knowledge about COVID-19, and perceived risk of COVID-19. Additionally, given the importance of trust in science in COVID-19 vaccine acceptance, our study also aims to explore its determinants so that we can contribute to better-targeted health communication campaigns that aim at both increasing trust and encouraging vaccine uptake.For our empirical exercise, we select a case of a heavy progression of the pandemic coupled with low trust in science: Hungary. As of autumn 2022, Hungary registered more than 2 million COVID-19 cases and almost 50 thousand COVID-related deaths. This put Hungary fifth in the world regarding the number of COVID-19 deaths per 100,000 capita. Even though vaccines became widely accessible by May 2021, at the time of our data collection (November 2022), only 62% of the population had received at least one dosage. While this figure is on par with the world average (61%), it is within the lowest quarter of the EU. Hungary also demonstrates low levels of trust in science (Farkas et al.2022), and conspiracy theories easily find their audience (Bíró-Nagy and Szászi, 2023). This provides a fertile ground for vaccine skepticism, hampering pandemic-mitigation efforts.Data provider: Marketing Resolutions Ltd. (Hungary)Replication code: Zsófia PappSoftware: R 4.4.0