Chinese Premier Li Keqiang visited the city of Wuhan on Monday to meet with health officials and examine the response to the outbreak of a coronavirus that has killed 80 people.
Wuhan is the center of the outbreak and people there and in several other cities face strict restrictions on movement as the government tries to prevent the virus from spreading.
Officials took an extra step Sunday to extend the Lunar New Year holiday three extra days to cut down on group gatherings.
The latest figures reported by Chinese health officials include more than 2,700 cases of people being sickened by the virus.
Cases have also been reported in Australia, Canada, France, Hong Kong, Japan, Macao, Malaysia, Nepal, Portugal, Singapore, South Korea, Taiwan, Thailand, the United States and Vietnam. The World Health Organization says most of those are people who had a travel history in Wuhan, with several others having contact with someone who traveled there.
There have been no reported deaths linked to the virus outside of China.
WATCH: Virus spreads to more countries
The head of the U.S. Centers for Disease Control and Prevention respiratory disease office, Nancy Messonnier, said Sunday there were five confirmed cases in the United States, and that all five people had direct contact with others in Wuhan.
The patients 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 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, when no signs or symptoms of the disease are present..
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. Many businesses have closed or asked employees to work from home.
The WHO recommends several steps to help protect people against acute respiratory infections. They include avoiding close contact with those already infected, frequent hand-washing and avoiding unprotected contact with farm animals and wild animals.