The clinical phenotype of COVID-19, caused by SARS-CoV-2, is remarkable for its wide range of severity among individual patients. Genetic variations are known to mediate part of these differences. To examine these differences, researchers in a new study used human induced pluripotent stem cells (iPSCs) from different genetically diverse individuals. These cells are used to model genetic disease since they contain the donor’s genetic information. Researchers use a panel of iPSCs from over 500 individuals. The researchers preferred undifferentiated iPSCs to reduce the time required to differentiate them, especially since infection is not always reliable.