Chinese Premier Li Keqiang on Monday visited Wuhan, the capital of Hubei province and centre of the outbreak.
The number of people killed in China by the coronavirus has risen to 80, with almost 3,000 confirmed ill.
The national new year holiday has been extended by three days to Sunday, in an attempt to contain the spread.
The number of deaths in Hubei province has climbed from 56 to 76, with four deaths elsewhere.
Wuhan is in lockdown and several other cities have imposed travel bans.
The overall number of confirmed cases in China is 2,744.
Some 461 are critically ill, while 51 people have been “discharged from hospital and cured”, the National Health Commission said.
But after the pre-new year travel surge, the prospect of half a billion people getting back on trains, planes and buses and crisscrossing the country again is the last thing the government wants, he adds.
According to the World Health Organization and national authorities, there have been at least 42 confirmed cases outside China.
Eight cases: Thailand
Five: USA, Australia
Four: Singapore, Taiwan, Malaysia
Three: France, Japan
Two: South Korea, Vietnam
One: Nepal, Canada
Almost all had recently been to Wuhan or had been in close contact with someone who had.
The virus is thought to have emerged from illegally traded wildlife at the Huanan seafood market in Wuhan.
Authorities have since temporarily banned the sale of all wildlife in China.
The virus itself is a new, or “novel” coronavirus – a family that normally affects animals.