Here are a few key points about coronavirus.
What is coronavirus?
The UN's health agency says that the outbreak of the disease in Wuhan is a never-before-seen strain belonging to a broad family of viruses ranging from the common cold to more serious illnesses such as SARS.
According to Arnaud Fontanet, head of the department of epidemiology at Institut Pasteur in Paris, the new strain is the seventh known type of coronavirus that humans can contract.
"We think that the source may have been animals sold at market and from there it passed to the human population," he told AFP.
The World Health Organization (WHO) says an "animal source seems the most likely primary source… with some limited human-to-human transmission occurring between close contacts."
The outbreak has caused alarm because of the link with SARS (Severe Acute Respiratory Syndrome), which killed 349 people in mainland China and another 299 in Hong Kong in 2002-2003.
Fontanet said the current virus strain was 80% genetically identical to SARS.
A total of 201 people have now been diagnosed with the virus in China, and the outbreak has already claimed 3 lives.
Time to panic?
Fontanet said that the coronavirus appears to be "weaker" than SARS in its current form, but cautioned that it could mutate into a more virulent strain.
"We don't have evidence that says this virus is going to mutate, but that's what happened with SARS," he said.
"The virus has only been circulating a short time, so it's too early to say."
As for person-to-person transmission – a key hallmark of pandemics – it may also be too early to tell for sure.
But Wuhan authorities said over the weekend that some of the new cases had "no history of contact" with the seafood market believed to be the center of the outbreak.
Authorities have pronounced the risk of human transmission "weak" but not impossible.
Fontanet said the fact that the virus had spread beyond China, to Japan and Thailand, was "starting to make us fear that interhuman transmission is possible."
Scientists with the MRC Centre for Global Infectious Disease Analysis at Imperial College in London warned in a paper last week that the number of cases in Wuhan was likely to be close to 1,700, much higher than the number officially identified.
WHO has advised that individuals should protect themselves against the virus by thoroughly washing their hands, covering their noses when they sneeze, thoroughly cooking meat and eggs, and avoiding close contact with wild or farm animals.
The best way of containing any disease outbreak is to rapidly confirm the source, according to Raina MacIntyre, from the University of New South Wales in Sydney.
"Tests are being done on animals in the Wuhan region and they should provide some insight," she said.
Experts said authorities must be vigilant and monitor travellers coming to and from Wuhan for signs of breathing problems.
Fontanet said health workers in China had responded admirably by rapidly carrying out testing among patients and linking the cases to the market in question.
"We've learned some lessons from SARS. We're better armed and more reactive," he said.
Adam Kamradt-Scott, an expert in the spread and control of infectious diseases at the University of Sydney, said China had "has been quick to share the genome sequencing of this novel coronavirus".
"This has enabled the identification of this new case in Japan," he said.
Fontanet said that such transparency was different to the start of the SARS epidemic, when China "hid the story for two or 3 months" at the start of the outbreak. – Rappler.com