One health disparities and COVID-19

Abstract

The global impact of the COVID-19 pandemic has disproportionately affected some communities and populations more than others. We propose that an interdisciplinary framework of 'One Health Disparities' advances understanding of the social and systemic issues that drive COVID-19 in vulnerable populations. One Health Disparities integrates the social environment with One Health perspectives on the interconnectedness of human, animal, and environmental health. To apply this framework, we consider One Health Disparities that emerge in three key components of disease transmission: exposure, susceptibility, and disease expression. Exposure disparities arise through variation in contact with COVID-19's causative agent, SARS-CoV-2. Disparities in susceptibility and disease expression also exist; these are driven by biological and social factors, such as diabetes and obesity, and through variation in access to healthcare. We close by considering how One Health Disparities informs understanding of spillback into new animal reservoirs, and what this might mean for further human health disparities.

Lay summary: One Health focuses on interconnections between human, animal, and environmental health. We propose that social environments are also important to One Health and help illuminate disparities in the coronavirus pandemic, including its origins, transmission and susceptibility among humans, and spillback to other species. We call this framework One Health Disparities.

Keywords: COVID-19; One Health; health disparities; social environment.

Figure 1.

One health disparities. The top of the figure illustrates a standard view of One Health and zoonotic disease in the context of SARS-CoV-2. Bats represent the likely reservoir of SARS-CoV-2, with transmission from bats to humans occurring directly or through bridge hosts (amplification hosts), such as livestock or animals in wet markets. Once in the human population, the virus successfully infected multiple new animal species, including mink, and other species are likely to be susceptible, such as other great apes. The bottom of the figure integrates One Health, social determinants of health, and health disparities within a framework of exposure, susceptibility and disease expression. We represent the social environment and exposure with a social network, revealing a gradient in exposure (top to bottom) that results in exposure disparities. Susceptibility and disease expression are combined here, given that they are difficult to disentangle without experimental studies, and also shown as a gradient (left to right). This results in a gradient of susceptibility and disease expression disparities. The figure shows an expected correlation between exposure and susceptibility-disease expression. However, outliers to this expected correlation will occur. For example, individual (a) is someone who has high exposure but low susceptibility (such as a healthcare worker) and individual (b) is someone who has high susceptibility but low exposure (such as an older person with comorbidities who is able to work from home to reduce exposure).