Behind the rapid spread was something that initially caught scientists off guard, baffled health authorities and undermined early containment efforts: The virus could be spread by seemingly healthy people. Researchers have exposed the frightening likelihood of silent spread of the virus by asymptomatic and presymptomatic carriers. Many scientists believe that during these days, people can spread virus just by talking, breathing or touching surfaces. As it became clearer that healthy people could spread the virus, U.S. health authorities opted not to wait for scientific certainty. (Sergio Flores/Getty Images)U.S. health officials blame China for delays in sharing information on silent spread.

Source: CBC News July 22, 2020 16:18 UTC