Coronavirus may be the 'Disease X' WHO cautioned about years ago

The disease has now spread to more than two dozen countries and territories

The World Health Organization cautioned years ago that a mysterious “disease X” could spark an international contagion. The new coronavirus, with its ability to quickly morph from mild to deadly, is emerging as a contender.

From recent reports about the stealthy ways the so-called Covid-19 virus spreads and maims, a picture is emerging of an enigmatic pathogen whose effects are mainly mild, but which occasionally — and unpredictably — turns deadly in the second week. In less than three months, it’s infected about 77,000 people, mostly in China, and killed more than 2,200.

“Whether it will be contained or not,