Political Party Affiliation and COVID-19 Vaccination Status in Japan, 2022.

Introduction: An association has been reported between political affiliations and vaccination worldwide. In Japan, a significant proportion of the population are non-partisans, and major political parties advocate COVID-19 vaccination. The association between supporting political parties and COVID-19 vaccination coverage in Japan remains unclear. This study aims to investigate the relationship between political party affiliation and COVID-19 vaccination status in Japan.  Methods: This study utilized data from large-scale nationwide internet surveys conducted in Japan in 2022, with a sample size of 21,162 participants. The surveys collected information on participants' COVID-19 vaccination status and political party affiliation. The political parties included in the analysis were the Liberal Democratic Party, the Constitutional Democratic Party, the Komeito, the Japanese Communist Party, the Japan Innovation Party (Nippon Ishin no Kai), and the Reiwa Shinsengumi, as well as non-partisans. Logistic regression analysis was performed to examine the relationship between political partisanship and COVID-19 vaccine status. The analysis controlled for potential confounding variables such as age, gender, socioeconomic status, and geographic location.

Results: The odds of being unvaccinated were lower for supporters of large political groups (e.g. Liberal Democratic Party {OR 0.6; 95% CI, 0.5-0.7}), while higher for small political groups (e.g. Reiwa Shinsengumi {OR 2.6; 95% CI, 1.9-3.6}), in comparison with non-partisan.

Conclusion: Political affiliation may be associated with vaccination disparities in Japan. Supporters of minor parties were more likely to be unvaccinated than those of the larger parties. However, this study has several limitations, including self-reporting bias and selection bias due to the Internet survey methodology.