Populism has fatally weakened the world’s ability to respond to COVID-19, by undermining the capacity of the structures and mechanisms of international law to address the pandemic. The pandemic has exposed as a fallacy a key tenet of populism – to protect the ‘people’ of a nation from external forces, including international law. In fact international law, through the principle of self-determination, enshrines the ability of peoples to determine their own political organization. But this does not preclude agreement at the international level on matters of common interest to humanity as a whole that require community action. The prevention of infectious disease is just such a case, which states have long agreed could not remain solely the preserve of national polities, but requires a common international response. This paper, placing the current crisis in light of the development of international health law, critically examines the response of key populist governments to COVID-19 in order to address the larger issue of the implications of populism for the fate of international law.