President Donald Trump said on Wednesday that the United States has a plan in place to contain the coronavirus outbreak.
Mr Trump made the statement hours after the first case of coronavirus had been diagnosed in the US.
The virus, also known as the Wuhan pneumonia, has killed nine people as of Wednesday with 440 confirmed cases. It is adapting and mutating, a Chinese health official said on Wednesday, creating challenges for health authorities in controlling the outbreak.
At the World Economic Forum annual meeting in Davos, Switzerland, Mr Trump said: "We do have a plan and we think it is going to be handled very well. We've already handled it very well. The CDC [Centres for Disease Control) is terrific. Very professional ..."
The first US resident to contract the new coronavirus, reported to be a man in his 30s, arrived in Seattle, US, from China on January 15, the CDC said.
"The patient sought care at a medical facility in the state of Washington, where the patient was treated for the illness," the CDC said.
The virus has so far spread to 15 Chinese provinces, the municipalities of Beijing, Tianjin and Shanghai, as well as Macau and Hong Kong, and Taiwan, South Korea, Japan and Thailand.
The virus originated from the central Chinese city of Wuhan at the end of last year, from a food market hosting illegal wildlife transactions, Gao Fu, the director general of China's Centre for Disease Control and Prevention, told a news briefing.
Mr Gao said authorities are still learning about the new virus, when asked to compare its deadliness to the Severe Acute Respiratory Syndrome (Sars) outbreak of 2003.
Authorities have confirmed human-to-human transmission of the virus and medical workers have been infected. The possibility of viral mutation has fed alarm.
Taiwan's Terry Gou, the billionaire founder of Apple supplier Foxconn, said on Wednesday he was advising company employees not to visit China over the coming Lunar New Year holiday, amid concerns over new coronavirus.
"The speed of contagion will be no less than Sars," Mr Gou said at the company's Lunar New Year party. "I advise everyone not to go to the mainland for this coming New Year holiday."
The virus is also hitting the Chinese economy with the Chinese stock market falling to its lowest level so far this year on Wednesday.
The Shanghai Composite Index dropped as much as 1.5 per cent. Yields on safe-haven Chinese 10-year government bonds dipped below 3 per cent for the first time since August. Chinese biotech companies and drug makers shares have surged.
The possibility of Chinese retail sales, tourism, hotel and catering and travel activities being affected over the Lunar New Year is very real but also in the first half of the year if the virus cannot be contained.
Chinese health authorities urged people in the city of Wuhan to avoid crowds and public gatherings as well as leaving the city. Live animals are now forbidden from entering the city.
Travel between North Korea and China, and vice versa, has been paused. Most tourists to North Korea are either Chinese or travel to the country through neighbouring China.
Rumours circulating on Chinese social media site Weibo claimed Chinese National Health Commission member Wang Guangfa has contracted the virus. The social media posts were censored but claims of Mr Wang's quarantine remained trending on Wednesday.