The severity of the rapidly spreading coronavirus outbreak in China that's claimed more than a dozen lives is still unknown, and the extent of its spread will only be clearer after the Lunar New Year holidays, said David Roche of Independent Strategy, CNBC reports.

Hundreds of millions of Chinese will traveling during the week-long holiday period as China celebrates the Spring Festival.

"The bad news is that the worst has yet to come, as the number of new infections is still on the rise," warned Larry Hu, economist at Macquarie Capital.

Much is still not known about the mysterious new virus that has killed 17 people so far and infected nearly 600 others worldwide. The disease, first discovered in the Chinese city of Wuhan, has spread to Beijing, Shanghai and other populated cities in the country. Cases in Thailand, Japan, South Korea and even the United States, have also been discovered.

The World Health Organization will convene again on Thursday, a day after deciding not to designate the outbreak of the virus as a global health emergency.