As coronavirus cases top 190,000 worldwide and 11,000 in the U.S., many people are still learning the best practices to protect themselves. In this special report, MSNBC journalist Ari Melber reports on hand-washing, a simple act that can prevent contracting the virus – when practiced correctly. Drawing on medical and academic research, this report explores how many people do not actually wash effectively to prevent viruses; how to fix that; why certain reminders and signs statistically increase the rate of washing; and the history and science behind this crucial everyday practice.