Chinese health authorities have said there were 7,711 confirmed cases in the country as of 29 January.
Infections have also spread to at least 16 other countries.
The World Health Organization (WHO) will meet on Thursday to discuss whether the virus constitutes a global health emergency.
"In the last few days the progress of the virus, especially in some countries, especially human-to-human transmission, worries us," WHO Director-General Tedros Adhanom Ghebreyesus said on Wednesday, pointing to Germany, Vietnam and Japan.
"Although the numbers outside China are still relatively small, they hold the potential for a much larger outbreak."
What is the coronavirus?
The virus is thought to have emerged from illegally traded wildlife at a seafood market in Wuhan, the capital of Hubei province and where most cases and deaths have been reported.
Though there have been a handful of cases where it is thought to have spread between people - most of the confirmed cases are people who are from Wuhan or had close contact with someone who had been there.
While there is no specific cure or vaccine for the virus, many people who contract it have only mild symptoms and do recover from it.
It can though cause severe acute respiratory infection and lead to death.
Like the similar Sars and influenza viruses, the new coronavirus is thought to be particularly a risk for elderly and people with pre-existing illnesses.
The city has effectively been sealed off and China has put numerous transport restrictions in place to curb the spread of the virus.
People who have been in Hubei Province are also being told by their employers to work from home until it is considered safe for them to return.
The Chinese Football Association has announced the postponement of all games in the 2020 season.
Several international airlines have stopped or scaled back their routes to China and companies from Starbucks to Tesla have closed their stores and production lines.
What are other countries doing?
Voluntary evacuations of hundreds of foreign nationals from Wuhan are underway to help people who want to leave the closed-off city and return to their countries.
Two flights to Japan have already landed at Tokyo's Haneda airport and the passengers are being screened at medical institutions. So far, three have tested positive for the virus, Japanese media report.
Around 200 US citizens have also been flown out of Wuhan and are being screened in the US.
A group of Singaporean citizens has also already been flown out while people from Wuhan stranded in Singapore due to flight cancellations have been flown back to China.
Flights to take British and South Korean citizens out of Wuhan have both been delayed after relevant permissions from Chinese authorities did not come through.
According to the UK government, the arriving passengers are to be put in "supported isolation" for 14 days with "all necessary medical attention".
Australia plans to quarantine its evacuees on Christmas Island, 2,000km (1,200 miles) from the mainland.
Two aircraft are due to fly EU citizens home with 250 French nationals leaving on the first flight.
Canada, the Philippines and Malaysia have also announced plans to fly their citizens out of Wuhan.
A growing number of countries are advising their citizens to avoid all non-essential travel to China. (BBC)
The body of a renowned environmental activist has been found in a well in central Mexico two weeks after he went missing, officials say.
Homero Gómez, 50, managed a butterfly sanctuary in the town of Ocampo in Michoacán state, a region notorious for its violent criminal gangs.
His body was found with no apparent signs of violence near where he was seen for the last time.
Prosecutors are still investigating the case.
Rights groups had earlier said they feared that Gómez might have been targeted because of his fight against illegal logging, one of the activities that criminal gangs in the area are involved in.
Gómez was last seen in person attending a meeting in the village of El Soldado on the afternoon of 13 January, and his family reported him missing the next day. Relatives told local media the conservationist had received threats from an organised crime gang.
More than 200 volunteers had joined the search for the environmentalist and, last week, the entire police forces of Ocampo and neighbouring Angangueo were detained for questioning.
It was not immediately clear how the body was found. In a tweet, the Michoacán public prosecutor's office said it had been taken for a post-mortem examination.
Gómez was a tireless campaigner for the conservation of the monarch butterfly and the pine and fir forests where it hibernates. The sanctuary he managed opened in November as part of a strategy to stop illegal logging in the area, which is a key habitat for the monarch butterfly.
In a video posted on his Twitter account shortly before his disappearance, he invited people to visit the sanctuary.
Since 2006, 60,000 people have disappeared in Mexico, many of them believed to have fallen victim to criminal gangs who kill anyone who could interfere with their illegal activities. (BBC)
The six-month inquiry will examine the causes of the fires, as well as how the state prepared and responded to them.
State Premier Gladys Berejiklian said the inquiry would consider how climate change, human activity and other factors had contributed to the blazes.
Bushfires have killed 25 people in NSW and damaged thousands of homes.
Ms Berejiklian said she hoped the inquiry would allow the state "to learn from this season and the catastrophic conditions we've faced, and apply these learnings for the future".
"NSW is incredibly proud of the efforts of all our emergency services personnel and volunteers throughout this ongoing bushfire season, but the scale of these fires has been unprecedented and we must leave no stone unturned," she said.
The inquiry, headed by former NSW Police deputy commissioner Dave Owens and former NSW chief scientist Professor Mary O'Kane, is set to begin in the coming days.
The inclusion of climate change in the probe comes amid debate over the issue in Australia, with critics accusing Prime Minister Scott Morrison of inaction.
Australia is one of the highest emitters of carbon pollution per capita, largely because it is still heavily reliant on coal-fired power.
Mr Morrison has insisted that Australia is meeting the challenge "better than most countries" and fulfilling international targets.
While climate change is not the direct cause of the bushfires, scientists have long warned that a hotter, drier climate would contribute to Australia's fires becoming more frequent and more intense.
A deadly new virus. Thousands of people infected. No cure. No vaccine.
We've been here many times before.
In the past five years alone, the world has faced outbreaks of Ebola, Zika, another coronavirus called Mers (Middle East Respiratory Syndrome), and now the virus simply known as "2019-nCoV".
It's already infected thousands of people and killed more than 100.
But unlike in many previous outbreaks, where vaccines to protect people have taken years to develop, research for a vaccine to help stem this outbreak got under way within hours of the virus being identified.
Chinese officials released its genetic code very quickly. That information helps scientists determine where the virus probably came from, how it might mutate as the outbreak develops, and how to protect people against it.
With technological advances and greater commitment from governments around the world to fund research on emerging diseases, research facilities were able to spring into action fast.
Unprecedented speed
At Inovio's lab in San Diego, scientists are using a relatively new type of DNA technology to develop a potential vaccine. "INO-4800 " - as it's currently called - with plans for it to enter human trials by the early summer.
Kate Broderick, senior vice-president of research and development at Inovio, said: "Once China had provided the DNA sequence of this virus, we were able to put it through our lab's computer technology and design a vaccine within three hours.
"Our DNA medicine vaccines are novel in that they use DNA sequences from the virus to target specific parts of the pathogen which we believe the body will mount the strongest response to.
"We then use the patient's own cells to become a factory for the vaccine, strengthening the body's own natural response mechanisms."
Inovio says if the initial human trials are a success, larger trials would follow, ideally in an outbreak setting in China "by the end of the year".
It is impossible to predict whether this outbreak is likely to have ended by then. But if Inovio's timeline goes to plan, the company says it will be the quickest a new vaccine has ever been developed and tested in an outbreak situation.
The last time a similar virus - Sars - emerged in 2002 - China was slow to let the world know what was happening. So by the time work on a vaccine started in earnest, the outbreak was almost over.
The timeline of 2019-nCoV
The work in these labs is being funded by the Coalition for Epidemic Preparedness Innovations (Cepi), which is made up of and funded by governments and philanthropic organisations from around the world.
It was created in the aftermath of the Ebola outbreak in West Africa to provide funding to accelerate the development of vaccines for new diseases.
Dr Melanie Saville, director of vaccine research and development at Cepi, said: "The mission is to make sure that outbreaks are no longer a threat to humanity and to develop vaccines for emerging infectious diseases."
'Molecular clamp'
Cepi is also funding two other programmes that are developing a vaccine for this new coronavirus.
The University of Queensland is working on a "molecular clamp" vaccine, which it says "enables targeted and rapid vaccine production against multiple viral pathogens."
Moderna Inc in Massachusetts has also joined forces with the US National Institute of Allergy and Infectious Diseases to accelerate its research.
The WHO is co-ordinating this global quest for a new vaccine. It says it is following the progress of a number of research facilities, including the three supported by Cepi.
Although efforts to come up with a vaccine for this new coronavirus have been accelerated, research is still at an early stage at all the facilities in the race to find a new vaccine. Clinical trials take time and are best carried out within an outbreak setting.
There are no guarantees any of the designs so far will be safe and effective enough to be used in the outbreak in China.
Ana Maria Henao-Restrepo from the WHO's Health Emergencies programme said: "We have developed a framework to inform decisions on which candidate vaccine(s) should be tested first.
"The experts will consider a number of criteria, including acceptable safety profile, induction of appropriate immune responses, and the timely availability of sufficient supplies of vaccine doses.
"Understanding the disease, its reservoirs, its transmission, its clinical severity and developing effective counter measures is critical for the control of the outbreak."
The WHO is due to decide which vaccine will be tested on humans first in the coming days. (BBC)