This article provides a systematic analysis of the proposal to use Covid-19 vaccination status as a criterion for admission of patients with Covid-19 to intensive care units (ICUs) under conditions of resource scarcity. The general consensus is that it is inappropriate to use vaccination status as a criterion because doing so would be unjust; many health systems, including the UK National Health Service, are based on the principle of equality of access to care. However, the analysis reveals that there are several unique features of Covid vaccination status in the context of a pandemic that make this issue disanalogous to cases (such as lung cancer caused by smoking) discussed previously. First, there is equality in access to care at the point of vaccination; the unvaccinated refuse the offer of preventive care when they decline vaccination, weakening their claim to ongoing care if they become ill (this is qualitatively different from 'poor lifestyle choices' such as smoking). Second, the decision of one person to refuse vaccination substantially increases the risk that they will become seriously ill and need ICU care; the person who chooses not to get vaccinated thus potentially increases the pressure on intensive care bed provision, as well as increasing the risk that he or she will infect others who in turn might end up needing ICU care. Third, justice cuts both ways, and giving unvaccinated patients equal priority may itself be unjust when other patients have reduced their risk of ending up on the ICU by getting vaccinated.