How Japan's COVID-19 vaccination policy shapes trust in governance: a relative deprivation approach.

This study investigates how Japan's central government's COVID-19 vaccination policy influenced public trust in the government during the pandemic. Using data from the Online Panel Survey of Stratification and Social Psychology (SSPW2021-Panel) and two-way fixed effects regression models, the research finds a nonlinear, U-shaped relationship between prefecture-level vaccination rates and trust in government. Initially, as vaccination rates increased, trust declined due to relative deprivation felt by unvaccinated individuals compared to their vaccinated peers; however, once vaccination surpassed a critical threshold (around 40–50%), trust began to recover as unvaccinated individuals became a minority. These findings highlight that even socially desirable policies can temporarily damage government trust through perceived inequalities in policy implementation, emphasizing the importance of considering social context and relative deprivation in public health policy design.