Examining the role of social environment on COVID-19 infections and vaccine uptake among migrants in Japan: Findings from nationwide surveys in 2021 and 2023

Studies have shown that migrants and ethnic minority groups were disproportionately affected by the COVID-19 pandemic, yet the role of the social environment in shaping their vulnerabilities remains underexplored in Japan. This study explored the experiences of migrants in Japan during the COVID-19 pandemic and examined the association between social environmental factors (i.e., population density, neighborhood deprivation, ethnic density, and social networks) and both COVID-19 infections and vaccination uptake. Two nationwide online surveys were conducted in 2021 and 2023 to capture migrants' experiences and analyze these associations during the middle and waning stages of the pandemic. Modified Poisson regressions with robust standard errors were applied for the analysis. The findings revealed the complex and evolving influence of social environmental factors on infections and vaccination uptake as the pandemic progressed. Larger neighborhood ties with co-nationals were associated with a higher risk of infection in 2021, while neighborhood population density, neighborhood deprivation, and ethnic density showed no significant association with infection in both surveys. Regarding COVID-19 vaccination, more social contacts with Japanese natives were negatively associated with vaccine hesitancy in 2021 and incomplete vaccination in 2023. Additionally, neighborhood deprivation was positively associated with vaccine hesitancy and incomplete vaccination in 2021 before adjusting for other variables. In anticipation of future pandemics, customized programs should be developed to address the unique healthcare needs of migrants and tailored to different stages of the pandemic.