COVID-19's silent spread: Evidence mounting that many infections are going undetected

In Iceland, nearly half of people with COVID-19 had no symptoms when they were swabbed for a scientific study. In the United States, preliminary results from a new antibody survey suggests as many as one in five New Yorkers may have been exposed to the novel coronavirus. And in the waters off the coast of Guam, more than 850 sailors on a navy warship have been infected in a massive outbreak - with roughly half reporting no symptoms when they were tested.