“When I heard this, I thought, ‘oh dear, this is worse than we anticipated.’ It means the infection is much more contagious than we originally thought,” said Dr. William Schaffner, a longtime adviser to the Centers for Disease Control and Prevention.

Schaffner added that this new piece of information called into question the current US practices for containing the virus so it doesn’t spread beyond the three cases that have already appeared in Washington state, California, and Illinois.

“Assuming that Dr. Ma is correct, we’re going to have to re-evaluate our strategy, that’s for sure,” said Schaffner, an infectious disease expert at Vanderbilt University Medical Center.

If Ma is correct – and information about this virus is constantly evolving — for about two weeks, people who don’t even know they’re sick can spread the virus, which has killed more than 50 people in China and infected thousands.