U.S. federal health officials say there are now five confirmed cases of the new China-based coronavirus and say they expect more.
The head of the Centers for Disease Control respiratory disease office, Nancy Messonnier, said Sunday all five victims had direct contact with others in Wuhan, the Chinese city where the disease is believed to have started.
All five are said to be in good condition, but are isolated in hospitals as doctors and health officials try to find out more about the virus. The CDC says it is investigating about 100 suspected cases in 26 states.
Chinese officials say 56 people have died and nearly 2,000 others in China have been infected.
National Health Commission Minister Ma Xiaowei said Sunday little is known about the virus. But doctors do know it has an incubation period that can range from one to 14 days. Ma said the virus is infectious during the incubation period, and is spreading more easily. He said infections are expected to continue to rise.
President Xi Jinping said China is facing a "grave situation" and experts and other resources would be concentrated at specific hospitals to treat severe cases of the illness.
The virus is believed to have emerged late last year in Wuhan, the capital of Hubei province, at a seafood market illegally selling wildlife. Chinese authorities have imposed a temporary ban on the selling of wildlife.
The virus hit China just as it was beginning the celebrations of the Lunar New Year, resulting in the canceling or the scaling back of festivities for tens of millions of Chinese.
Tourist destinations are closed and school closings have been extended, in an effort to stop the spread of the virus. Public transportation has been severely restricted.
The U.S. said Sunday it is making plans to evacuate its diplomatic staff and other American citizens from Wuhan. The State Department warned, however, that accommodations for private citizens would be "extremely limited."
France and Russia are also planning evacuations for their citizens in Wuhan.
The deadly virus is spreading around the world. Cases have been reported in Australia, Canada, France, Hong Kong, Japan, Macao, Malaysia, Nepal, Portugal, Singapore, South Korea, Taiwan, Thailand, the U.S. and Vietnam.