At the psychological core of society's response to a pandemic is the Other. Multiple Others. The infected are Others until they recover, needing isolation and exclusion. Those who recklessly or even intentionally increase the risk of infection are Others, in breach of societal norms and deserving of denunciation.
The racist demonisation of people of colour in relation to the disease uses traditional Other stereotypes of non-white people as unclean. And ultimately, in an epidemiological twist on Sartre's l'enfer, c'est les autres, all people other than your own household become Others, to be kept socially distanced, potential sources of plague and death.
That voters in states like Western Australia and Queensland are happy to either keep their borders sealed against interstate travel, or exclude large swathes of the external population, is vexing to the federal government and business who want borders reopened.