A new virus that has killed nine people, infected hundreds and reached the United States could mutate and spread, China warned Wednesday, as authorities urged people to steer clear of the city at the heart of the outbreak.
The coronavirus has caused alarm because of its similarity to SARS (Severe Acute Respiratory Syndrome), which killed nearly 650 people across mainland China and Hong Kong in 2002-2003.
With hundreds of millions of people travelling across China this week for the Lunar New Year holiday, the National Health Commission announced measures to contain the disease -- including sterilisation and ventilation at airports and bus stations, as well as inside planes and trains.
In Wuhan, the epicentre of the epidemic, large public events were cancelled and international football matches were moved to new location. Visitors were urged to stay away, while residents were advised to not to leave the central city of 11 million people.
The illness is mainly transmitted via the respiratory tract and there "is the possibility of viral mutation and further spread of the disease", health commission vice minister Li Bin told a news conference in Beijing.
The virus has now infected at least 440 people across the country, with most cases in Wuhan. Li added that 1,394 people are still under medical observation.
The World Health Organization (WHO) started an emergency meeting Wednesday to determine whether to declare a rare global public health emergency over the disease, which has now been detected in the United States, Taiwan, Thailand, Japan, South Korea and Macau.
The first case in the United States -- a Seattle resident in his 30s -- is in good condition, American officials said.
The Chinese government has classified the outbreak in the same category as the SARS epidemic, meaning compulsory isolation for those diagnosed with the illness and the potential to implement quarantine measures.
But they still have not been able to confirm the exact source of the virus.
"We will step up research efforts to identify the source and transmission of the disease," Li said, although he said experts believe "the cases are mostly linked to Wuhan".
Countries have been intensifying efforts to stop the spread of the pathogen -- known by its technical name 2019 Novel Coronavirus (2019-nCoV) -- as the number of cases jumped.
Plane passengers are facing screening measures at five US airports and a host of transport hubs across Asia.
North Korea will ban foreign tourists entirely to protect itself against the virus, according to a major tour operator.
A prominent expert from China's National Health Commission confirmed this week that the virus can be passed between people.
However, animals are suspected to be the primary source of the outbreak.
A price list circulating online in China for a business at the Wuhan market lists a menagerie of animals or animal-based products including live foxes, crocodiles, wolf puppies and rats. It also offered civets, the animal linked to SARS.
"We already know that the disease originated from a market which conducted illegal transaction of wild animals," said Gao Fu, director of the Chinese centre for disease control and prevention.
He said it was clear "this virus is adapting and mutating".
Hong Kong and British scientists have estimated that between 1,300 and 1,700 people in Wuhan may have been infected.
Health authorities are urging people to wash their hands regularly, avoid crowded places, get plenty of fresh air and wear a mask if they have a cough.
Anyone with a cough or fever was urged to go to hospital.
Surgical masks and antibacterial products were starting to sell out on some popular online sites and pharmacies.
"These days, I wear masks even in places that are not too crowded, although I wouldn't have done so in the past," said Wang Suping, 50, who works at a Beijing arts school.
At the capital's main international airport, the majority of people were wearing masks.
Hong Kong flag carrier Cathay Airlines said they agreed to allow staff to wear surgical masks on mainland China flights, adding they would offer masks and antiseptic wipes to passengers travelling from Wuhan to the city.
In Wuhan, police were conducting vehicle spot checks for live poultry or wild animals leaving and entering the city, state media said. Officials also screened people on roads, the airport and the train station for fevers.
"If it's not necessary we suggest that people don't come to Wuhan," Mayor Zhou Xianwang told state broadcaster CCTV.
The local government has cancelled major public activities and banned tour groups from heading out of the city.
Women's football qualifiers for the Tokyo Olympic Games that were supposed to be held in Wuhan between February 3-9 were moved to the eastern city of Nanjing.
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