FIVE million people fled Wuhan in fear of the deadly coronavirus just before the city was put on lockdown, it has been revealed.
The virus has now claimed 81 lives and infected at least 2,801 people around the world - and experts say it's getting stronger.
Health officials in China have warned that the ability of the virus to spread is increasing.
In a bid to curb it, authorities have extended the Lunar New Year holiday by three days from 30th January to 2nd February.
The head of the National Health Commission in China, Ma Xiaowei, warned that battling the virus is difficult as it had been discovered that it can spread during the incubation period, which lasts one to 14 days, unlike SARS.
Xiaowei said "there are signs...the virus is becoming more transmissible" with hidden carriers "making controlling the outbreak a lot more difficult".
COMPLETE SHUTDOWN
Wuhan's city Mayor Zhou Xianwang said around nine million people stayed behind after the lockdown was put in place on Thursday.
According to reports, 2,700 people in China remain under observation, 533 cases were confirmed as of Sunday and there might be an extra 500 cases confirmed in the next coming days.
In Shanghai, officials have stopped all businesses apart from medical firms, supermarkets and utilities from returning to work until February 10.
Wuhan is building two hospitals, one with 1,500 beds and another with 1,000, for the growing number of patients. The first is scheduled to be finished next week.
Increasingly drastic anti-disease efforts began with the Jan. 22 suspension of plane, train and bus links to Wuhan.
That lockdown has expanded to a total of 17 cities with more than 50 million people in the most far-reaching disease-control measures ever imposed.
IT'S STILL SPREADING
At least 44 cases have been confirmed abroad including Thailand, the United States and Australia.
The U.S. cases are in Washington state, Chicago, southern California and Arizona.
China also reported five cases in Hong Kong and two in Macao.
The youngest patient is a 9-month-old girl in Beijing.
But there have been no deaths outside China.
The epidemic has revived memories of the SARS outbreak that originated in China and killed nearly 800 people.
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The chief of the Chinese Centre for Disease Control and Prevention, Gao Fu, said that the epidemic "is still growing" but confirmed there had been no signs the virus is mutating.
Currently, workers are checking people's temperatures before allowing then into Wuhan.
And some Wuhan citizens are still tourists in other countries.