Association of Socioeconomic Characteristics With Disparities in COVID-19 Outcomes in Japan

Yuki Yoshikawa,Ichiro Kawachi

doi:10.1001/jamanetworkopen.2021.17060

Abstract

Socioeconomic factors in the disparities in COVID-19 outcomes have been reported in studies from the US and other Western countries. However, no studies have documented national- or subnational-level outcome disparities in Asian countries. To assess the association between regional COVID-19 outcome disparities and socioeconomic characteristics in Japan. This cross-sectional study collected and analyzed confirmed COVID-19 cases and deaths (through February 13, 2021) as well as population and socioeconomic data in all 47 prefectures in Japan. The data sources were government surveys for which prefecture-level data were available. Prefectural socioeconomic characteristics included mean annual household income, Gini coefficient, proportion of the population receiving public assistance, educational attainment, unemployment rate, employment in industries with frequent close contacts with the public, household crowding, smoking rate, and obesity rate. Rate ratios (RRs) of COVID-19 incidence and mortality by prefecture-level socioeconomic characteristics. All 47 prefectures in Japan (with a total population of 126.2 million) were included in this analysis. A total of 412 126 confirmed COVID-19 cases (326.7 per 100 000 people) and 6910 deaths (5.5 per 100 000 people) were reported as of February 13, 2021. Elevated adjusted incidence and mortality RRs of COVID-19 were observed in prefectures with the lowest household income (incidence RR: 1.45 [95% CI, 1.43-1.48] and mortality RR: 1.81 [95% CI, 1.59-2.07]); highest proportion of the population receiving public assistance (1.55 [95% CI, 1.52-1.58] and 1.51 [95% CI, 1.35-1.69]); highest unemployment rate (1.56 [95% CI, 1.53-1.59] and 1.85 [95% CI, 1.65-2.09]); highest percentage of workers in retail industry (1.36 [95% CI, 1.34-1.38] and 1.45 [95% CI, 1.31-1.61]), transportation and postal industries (1.61 [95% CI, 1.57-1.64] and 2.55 [95% CI, 2.21-2.94]), and restaurant industry (2.61 [95% CI, 2.54-2.68] and 4.17 [95% CI, 3.48-5.03]); most household crowding (1.35 [95% CI, 1.31-1.38] and 1.04 [95% CI, 0.87-1.24]); highest smoking rate (1.63 [95% CI, 1.60-1.66] and 1.54 [95% CI, 1.33-1.78]); and highest obesity rate (0.93 [95% CI, 0.91-0.95] and 1.17 [95% CI, 1.01-1.34]) compared with prefectures with the most social advantages. Among potential mediating variables, higher smoking rate (RR, 1.54; 95% CI, 1.33-1.78) and obesity rate (RR, 1.17; 95% CI, 1.01-1.34) were associated with higher mortality RRs, even after adjusting for prefecture-level covariates and other socioeconomic variables. This cross-sectional study found a pattern of socioeconomic disparities in COVID-19 outcomes in Japan that was similar to that observed in the US and Europe. National policy in Japan could consider prioritizing populations in socially disadvantaged regions in the COVID-19 response, such as vaccination planning, to address this pattern.

Highlights

Since the emergence of SARS-CoV-2 in 2019, more than 100 million cases of COVID-19 and 2.3 million deaths from COVID-19 have been reported worldwide as of February 14, 2021.1 older age has been shown to be a major risk factor of COVID-19 mortality,[2] several US studies have suggested that morbidity and mortality from this disease are associated with socioeconomic circumstances, including income, educational attainment, employment in service or retail industry, area poverty level, unemployment, household crowding, and race/ethnicity.[3,4,5,6]Understanding the sources of vulnerability to COVID-19 is essential for planning and delivery of interventions, such as deciding which individuals or groups should receive priority for the vaccine
This cross-sectional study found a pattern of socioeconomic disparities in COVID-19 outcomes in Japan that was similar to that observed in the US and Europe
For variables that we considered to be potential mediating variables of an association between socioeconomic circumstances and COVID-19 outcomes, we further adjusted model 2 for household income adjusted by regional price parities, Gini coefficient, the proportion of the population receiving public assistance, educational attainment, and unemployment rate, a process we termed model 3

Summary

Introduction

Since the emergence of SARS-CoV-2 in 2019, more than 100 million cases of COVID-19 and 2.3 million deaths from COVID-19 have been reported worldwide as of February 14, 2021.1 older age has been shown to be a major risk factor of COVID-19 mortality,[2] several US studies have suggested that morbidity and mortality from this disease are associated with socioeconomic circumstances, including income, educational attainment, employment in service or retail industry, area poverty level, unemployment, household crowding, and race/ethnicity.[3,4,5,6]Understanding the sources of vulnerability to COVID-19 is essential for planning and delivery of interventions, such as deciding which individuals or groups should receive priority for the vaccine. Since the emergence of SARS-CoV-2 in 2019, more than 100 million cases of COVID-19 and 2.3 million deaths from COVID-19 have been reported worldwide as of February 14, 2021.1 older age has been shown to be a major risk factor of COVID-19 mortality,[2] several US studies have suggested that morbidity and mortality from this disease are associated with socioeconomic circumstances, including income, educational attainment, employment in service or retail industry, area poverty level, unemployment, household crowding, and race/ethnicity.[3,4,5,6]. Japan reported the first case of COVID-19 on January 16, 2020.14 In Japan, local public health centers play a pivotal role in the pandemic response, including triaging, testing, allocating individuals to hospitals, and contact tracing. During the first wave of the pandemic, clusters of COVID-19 cases were reported in the Tokyo, Aichi, and Osaka metropolitan areas as well as the northern island of Hokkaido (which is its own prefecture). The first outbreak in Hokkaido was believed to be linked to travelers from China.[16]

Methods

Results

Discussion

Conclusion