The death toll from the coronavirus outbreak has risen to 170, and a confirmed case in Tibet means it has reached every region in mainland China. Chinese health authorities said there were 7,711 confirmed cases in the country as of 29 January. Infections have also spread to at least 15 other countries.

The World Health Organization (WHO) will meet on Thursday to again consider 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.

He named Germany, Vietnam and Japan, where there have been cases of people catching the virus from others who have been to China. "Although the numbers outside China are still relatively small, they hold the potential for a much larger outbreak," the WHO chief said. More people have now been infected in China than during the Sars outbreak in the early 2000s, but the death toll remains far lower. Sars, also a coronavirus, caused acute respiratory illness.

Researchers are racing to develop a vaccine to protect people from the virus. One lab in California has plans for a potential vaccine to enter human trials by June or July. Voluntary evacuations of hundreds of foreign nationals from Wuhan are under way to help people who want to leave the closed-off city and return to their countries.

The UK, Australia, South Korea, Singapore and New Zealand are expected to quarantine all evacuees for two weeks to monitor them for symptoms and avoid any contagion. Australia plans to quarantine its evacuees on Christmas Island, 2,000km (1,200 miles) from the mainland in a detention centre that has been used to house asylum seekers.

Singapore is setting up a quarantine facility on Pulau Ubin, an island north-east of the city-state’s mainland.

Although questions have been raised about transparency, the WHO has praised China’s handling of the outbreak. President Xi Jinping has vowed to defeat what he called a “devil” virus.

The central province of Hubei, where nearly all deaths have occurred, is in a state of lockdown. The province of 60 million people is home to Wuhan, the heart of the outbreak. 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 are also being told by their employers to work from home until it is considered safe for them to return.

The virus is affecting China’s economy, the world’s second-largest, with a growing number of countries advising their citizens to avoid all non-essential travel to the country.

Several international airlines have stopped or scaled back their routes to China and companies like Google, Ikea, Starbucks and Tesla have closed their shops or stopped operations.

There have been reports of food shortages in some places. State media says authorities are “stepping up efforts to ensure continuous supply and stable prices”.

The Chinese Football Association has announced the postponement of all games in the 2020 season.

Meanwhile, 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.