Heightened precautions are being taken in China and elsewhere at the moment, as governments are trying to control the outbreak of coronavirus, that threatens to grow.
Anxieties around the virus intensified after Chinese government expert Zhong Nanshan revealed that it can be spread between humans. Authorities had previously said there was no evidence of human-to-human transmission.
Chinese authorities have now advised people to stop travel into and out of Wuhan, the city at the centre of a new virus outbreak that has killed nine.
So far, at least 17 people have died, CNN has reported, and hundreds have been infected. So, should we be worried?
What is coronavirus and where has it spread?
The virus, known also as 2019-nCoV, is thought to be a new strain of coronavirus that has not previously been identified. The new type of coronavirus appears to have originated in the central city of Wuhan, which has reported 198 cases. Initial symptoms of the novel coronavirus include fever, cough, tightness of the chest and shortness of breath.
Others who have been diagnosed in Beijing, Shanghai and southern Guangdong province had also visited Wuhan. Internationally, four cases of coronavirus have been confirmed among Chinese travellers in South Korea, Japan and Thailand.
There has been concern that the outbreak is similar to Sars (severe acute respiratory syndrome), a different coronavirus that spread from China to more than a dozen countries in 2002-2003.
When Sars first infected people in southern China, the Chinese government initially tried to conceal the severity of the epidemic, which ended up killing nearly 800 people. The cover-up was exposed by a high-ranking physician.
Gabriel Leung, dean of medicine at the University of Hong Kong, said Chinese authorities have responded much more quickly this time.
Where did the virus come from?
The first cases identified late last month were among people connected to the Huanan Seafood Wholesale Market in Wuhan. The first patients were suspected to have contracted the virus from animals, but human-to-human transmission was confirmed late on Monday.
Mr Zhong, a government expert who helped expose the scale of Sars, told Chinese state broadcaster CCTV that two people in Guangdong province caught the virus from family members.
Fifteen medical workers have also tested positive for the virus, the Wuhan Municipal Health Commission announced. Previously, the commission said no-one who came into close contact with patients, including health professionals, were infected.
Professor Leung, who was heavily involved in the response to Sars, said modelling shows that cases will multiply over the coming weeks but the outbreak will gradually lose momentum as precautionary measures take effect.
What measures are other countries taking?
Numerous nations have adopted screening measures for travellers arriving from China, especially those from Wuhan.
Australia’s chief medical officer Brendan Murphy said his country will be increasing airport screening. Australia receives a significant number of travellers from China, including three direct flights a week from Wuhan into Sydney, and these flights will be met by border security and biosecurity staff for assessments.
Japan, South Korea, Hong Kong and other places with extensive travel links to China are also enacting stricter screening measures. At least three US airports have started screening incoming airline passengers from central China. Japanese prime minister Shinzo Abe said: “We need to step up our caution levels as the number of patients is continuing to rise in China. Please take every possible precaution.”
Health authorities in the UK are not screening arrivals on the flights from Wuhan to Heathrow.
Is it safe to travel there?
The World Health Organization said earlier in the week: “Based on currently available information, WHO does not recommend any restriction of travel or trade.”
However, advice changed on 22 January. National Health Commission vice-minister Li Bin said in one of the first public briefings since the beginning of the outbreak: “Basically, do not go to Wuhan. And those in Wuhan please do not leave the city.”
Authorities also reportedly said that the country was now at the “most critical stage” of prevention and control.
It emerged that Britain would start enhanced monitoring of all passengers who arrived on direct flights from the Chinese city of Wuhan to tackle the threat of the virus.
Passengers on the direct weekly flights to London’s Heathrow Airport from Wuhan, will be checked for symptoms and given advice about what to do if they become ill, The Department of Health and Social Care and Public Health England said in a statement on Wednesday.