Covid-19 is officially a pandemic. It is a novel infection with serious clinical manifestations, including death, and it has reached at least 124 countries and territories. Although the ultimate course and impact of Covid-19 are uncertain, it is not merely possible but likely that the disease will produce enough severe illness to overwhelm health care infrastructure. Emerging viral pandemics “can place extraordinary and sustained demands on public health and health systems and on providers of essential community services.” Such demands will create the need to ration medical equipment and interventions.