US health authorities said they were working on a vaccine, but that it would take months to develop
The United States and Japan evacuated their nationals from a quarantined city while British Airways suspended flights to mainland China as deaths from a new virus leapt to 133 and a government economist predicted a huge hit to the economy.
Beijing's pledge to slay the "devil" coronavirus has won the trust of the World Health Organisation (WHO) but confirmation of another 1,459 cases - taking the total to 5,974 in China - only fuelled public alarm around the world.
Deaths from the flu-like virus also rose by 26 to 133.
Almost all have been in the central province of Hubei, the capital of which is Wuhan, where the virus emerged last month in a live wild animal market.
The situation remained "grim and complex," Chinese President Xi Jinping acknowledged.
In many Chinese cities, streets were largely deserted with the few who ventured out wearing masks. Starbucks stores in Beijing required people to have temperatures taken and posted notices saying it was a state requirement to wear masks inside.
There was relief, however, among those evacuated from Hubei province, home to about 60 million people and under virtual lockdown. "I was extremely worried that I was stuck there," said Takeo Aoyama, who arrived in Tokyo on a chartered plane carrying 206 Japanese out of Wuhan, with more flights planned.
Two of the Japanese evacuated had symptoms of pneumonia but coronavirus had not been confirmed, medics said.
Breakthrough in Australia?
In what could be a major step towards taming the disease, scientists in Australia said they had developed a lab-grown version of the coronavirus, the first to be recreated outside China.
The US Centers for Disease Control and Prevention said about 210 Americans had been flown out of Wuhan. Those on board the aircraft would be screened several times and evaluated on arrival in California, it said in a statement released via the US embassy in Beijing.
A US government official told Reuters 50 diplomats and contractors were among the passengers.
Australia said it would help some citizens leave and then quarantine them on Christmas Island in the Indian Ocean, best known for housing asylum seekers.
US officials said the White House was weighing whether to suspend flights to China. It was holding daily meetings on the outbreak and monitoring China-US flights as a likely source of infection, sources briefed on the matter said, though it had decided against suspending air traffic for the time being.
The number of cases in China now exceeds its tally of 5,327 infected with the Severe Acute Respiratory Syndrome (SARS) coronavirus that killed about 800 people globally in 2002 and 2003.
While some experts believe the new strain, known as "2019-nCoV," is not as deadly as SARS, alarm has grown over its rapid spread and many unknown attributes, such as how lethal it is.
Like other respiratory infections, it is spread by droplets from coughs and sneezes, with an incubation time between one and 14 days. There are signs it may spread before symptoms show.
About 60 cases, but no deaths, have been reported in 15 other countries, including the United States, France and Singapore.
In the first known cases in the Middle East, the United Arab Emirates (UAE) diagnosed four members of a Chinese family who arrived from Wuhan with the coronavirus.