BEIJING: Chinese authorities and the World Health Organization (WHO) said a new strain of coronavirus is behind the outbreak of pneumonia in the central city of Wuhan, which has erupted just ahead of the Chinese New Year, the country's biggest festival.
Some experts say the strain may not be as deadly as some other strains of coronavirus such as Severe Acute Respiratory Syndrome (SARS), which killed nearly 800 people worldwide during a 2002/03 outbreak that also originated from China.
But little is known about the new virus, including its origin and how easily it can be transmitted between humans.
As of Tuesday (Jan 21), 291 people have fallen ill with the new coronavirus in China, with four dead.
The majority of the cases have been in Wuhan, although the disease has since spread to other Chinese cities, including Beijing, Shanghai and Shenzhen.
The virus has also spread beyond China: Thailand has reported two confirmed cases, while Japan and South Korea have one case each.
LITTLE KNOWN ABOUT VIRUS ITSELF
China's National Health Commission said in a statement on Jan 19 the source of the virus hasn't been found and that its transmission path has not been fully mapped.
The outbreak is strongly linked to a seafood market in Wuhan, but some patients diagnosed with the new coronavirus deny exposure to this market.
The WHO says an animal source appears most likely to be the primary source of the outbreak and that some limited human-to-human transmission is occurring.
Zhong Nanshan, a renowned scientist at the National Health Commission who helped expose the scale of the SARS outbreak, warned on Monday that the virus can be transmitted from human to human.
Fifteen medical workers who looked after pneumonia patients in Wuhan have been infected.
There is no vaccine for the new virus. Symptoms include fever, difficulty in breathing, coughing as well as pneumonic infiltrates in the lungs.
Chinese authorities have stepped up monitoring and disinfection efforts ahead of the Chinese New Year holiday in late January, when many of the country's 1.4 billion people will travel domestically and overseas.
READ: Wuhan pneumonia virus casts shadow over Chinese New Year festival
Airport authorities in the United States as well as many Asian countries, including Singapore, Japan, Thailand and South Korea, have stepped up screening of passengers from Wuhan.
The World Health Organization sent directives to hospitals around the world on infection prevention and control.