The new coronavirus doesn’t just kill by storming lungs and other organs. It also kills by besieging health care systems.

If left to swirl in a community unchecked for a few weeks, the virus can whip up a tsunami of cases that crash into urgent care clinics, emergency departments, and intensive care units, quickly washing out beds, supplies, and staff.

In such a crisis, doctors must make heart-wrenching decisions about which patients get the last beds and which get scarce ventilators and respiratory therapists. At the same time, they’re likely facing shortages of personal protective equipment (PPE), such as masks and gowns. Rationing and reusing such items leads to more nurses and doctors getting sick. That means fewer health care workers to wade through the flood of patients. Some may even join their patients in needing critical care.