In this paper, we explored the associations between COVID-19 vaccination and variables including those on socioeconomic status (employment type, household income, educational background, amount of deposits and savings). We used the 4th wave (conducted from 20 to 27 July 2021) of a 5-wave internet survey. Study samples were limited to those aged 40-64. Multivariate logistic regression analyses showed that self-employed workers, non-regular workers, and people not in the labor force were less likely to have been vaccinated than regular employees. Graduates of junior and senior high school only were less likely to have been vaccinated than graduates of four-year colleges. People with lower household income were less likely to have been vaccinated. In addition, people living alone, living with children, and living with parents were less likely to have been vaccinated than those living with a spouse but not with children or parents.