How to capture the individual and societal impacts of syndemics: the lived experience of COVID-19

The value of syndemic thinking is that it ‘brings together the environment and individual embodied experience to think about what types of interventions matter—from social policy to clinical practice’.4 In 2019, Lancet commissioned a report on the global syndemic of obesity that highlighted the ‘multilayered and multidimensional array of factors implicated in the dramatic global rise of obesity, undernutrition and climate change’.5 It should come as no surprise that we are now invited to view COVID-19 not as a pandemic but a syndemic.6 The characterisation fits what we know of the disease since both its spread and its lethality are strongly shaped by the impact of comorbid chronic health problems, especially the non-communicable diseases of hypertension, obesity, diabetes, cardiovascular and chronic respiratory diseases, and cancers.7 There is also evidence that COVID-19 has a greater impact on social groups that experience greater social and economic inequality.8 Confirming the underlying hypothesis of syndemic theory, COVID-19 infection and mortality patterns have been shown to differ across countries and regions, and early evidence suggests that they depend at least to some extent on the social, political and economic context. Potentially more useful is to pursue the insight that syndemics require a ‘systems-thinking’ approach, and that it is both naïve, and ineffective, to reduce the social response to COVID-19 to the simple narrative of personal protective measures (PPM) (including the use of protective masks and physical distancing) and vaccination towards herd immunity, while ignoring the ‘context of the human host, its immune system, microbiome and economic, social and natural environment’.15 No doubt it is essential to appreciate the complexity of interacting factors in the prevention and response to COVID-19, as it is to recognise that society is a complex system that resists simplistic causal explanations.16 Yet even staunch proponents of the syndemic approach point to its Achilles’ heel—the fact that ‘the theory of syndemics has received scant empirical support either for its concept of disease interaction or for the model of mutually causal epidemics…[illustrating] important methodological gaps in the literature’.17 If finding suitable causal models for disease interaction—especially between communicable and non-communicable diseases—is a methodological challenge, adding the broader societal context increases this challenge exponentially. [...