The slogan that ‘the virus doesn’t discriminate’ has been belied by the emergence of stark and persistent disparities in rates of infection, hospitalisation, and death from Covid-19 between various social groups. I focus on two groups that have been disproportionately affected, and that have been constructed or designated as particularly ‘at-risk’ during the Covid-19 pandemic: racial or ethnic minorities and fat people. I trace the range of narratives that have arisen in the context of explaining these disparities, in both the scientific literature and wider expert and public discourse. I show that the scientific and public narratives around these groups have differed significantly, revealing contested and competing conceptions of the basis of these categories themselves. These different conceptions have important impacts on the kinds of interventions that become possible or desirable. I show that in the case of racial or ethnic disparities, genetic narratives have been combatted by a strong focus on structural racism as a driver of pandemic inequalities. However, in the case of fatness, individualising and stigmatising narratives have dominated discussions. I suggest that, given racial or ethnic differences in prevalence of fatness, and scholarship casting anti-fatness as historically racialised, the stigmatisation of fatness disproportionately affects racial or ethnic minorities in terms of placing individual blame or responsibility for the increased burden of Covid-19 on these groups. Despite widespread acknowledgement of the role of structural racism in driving racial inequalities in the burden of Covid-19, anti-obesity rhetoric and research provides a ‘backdoor’ to placing blame on individuals from racial minorities.