Disparities in Coronavirus Disease 2019 Mortality among Japanese and Non-Japanese Residents: A Natural Experimental...

Universal health coverage has been cited as a critical factor in Japan's success in limiting mortality due to coronavirus disease 2019 (COVID-19). It is unclear if this success extended to non-Japanese residents, especially prior to roll out of COVID vaccines. Non-Japanese residents represent a growing minority of Japan's population, so this study aimed to assess any disparities in COVID-19 mortality between Japanese nationals and non-Japanese residents.

In this natural experiment, mortality due to COVID-19 was derived from death certificate data (2020-2021) registered by the Ministry of Health, Labour and Welfare (MHLW). Mortality rates were compared between Japanese nationals and non-Japanese residents, and then mortality was further explored by nationality. (South) Korean residents were identified as a subgroup of interest due to their status as the most populous non-Japanese nationality historically and their disproportionately high mortality rates. Age-standardized mortality rates and years of potential life lost (YPLL) were computed using vital statistics and life expectancy data from MHLW.

Of the 20,775 COVID-19 deaths in 2020/21, 98.3% were Japanese nationals, while non-Japanese residents accounted for the remaining 358 deaths. The nationwide age-standardized mortality rate was 16.5 per 100,000 individuals, with 14.9 for non-Japanese residents. Among older adults (≥65 years), the mortality rate for non-Japanese residents was 152.3 per 100,000, compared to 52.5 for the general population. Koreans accounted for 193 (53.9%) of non-Japanese deaths. Crude mortality rate was 51.5 per 100,000 for this group, sharply increasing among older adults (162.1). Total YPLL due to COVID-19 in 2020/21 was 76,544.1 years, with YPLL rates of 59.5 years per 100,000 among Japanese nationals, 178.4 for non-Japanese residents, and 268.2 for Koreans.

Notable disparities in COVID-19 mortality were uncovered, particularly among older non-Japanese and Korean residents. With growing diversity domestically, these findings suggest a need for institutional monitoring of health outcomes by nationality to better inform equitable public health in Japan.