Dr. Matthew Wynia, an ethicist and infectious disease physician at the University of Colorado [Anschutz Medical Campus], said that health officials faced a frightening trade-off in choosing between a pause and warning: They would know only hypothetically the lives a pause may have cost, but they would know exactly who may have suffered or died from clots. Because of how unusual this disorder is, Dr. Wynia said, a typical warning to physicians would not have grabbed as much attention and “not have made the impact this did.”