The killer coronavirus outbreak that is rapidly sweeping the world and has now killed 106 people will last for several more months and won't die down until after the summer, scientists fear.
Researchers closely tracking the escalating crisis warn the never-before-seen virus will afflict tens of thousands of people as it continues its rampage across Asia.
It comes as scientists have warned the world is still at least two months away from a trial of a vaccine against the SARS-like infection, which has so far struck down more than 4,500 people. Germany last night became the latest country to record a case.
Leading experts have admitted the 'best case scenario' is that the worsening crisis will die down after summer, while others have issued the chilling warning: 'It's not something that's going to end the next week or next month.'
Professor David Fisman, who wrote an analysis of the virus for the International Society for Infectious Diseases, said: 'The best case scenario, you would have something... where we go through the spring into the summer, and then it dies down.
More than 4,500 people around the world are now confirmed to have caught the coronavirus and 106 people have died, all of them in China. Germany, Sri Lanka and Cambodia yesterday became the latest countries to declare infections
Thai Airways employees are pictured disinfecting an empty plane cabin at Suvarnabhumi International Airport in Bangkok today, January 28. Thailand has eight confirmed coronavirus cases – the most outside of China
Passengers arriving at Nanjing Railway Station in China have their temperatures checked by staff who are looking to see if anyone has a high fever, a sign of infection
Security guards stand beside a disaster relief tent in Hunan province, near the border of Hubei where Wuhan is the capital. Photographed today, January 28
'It's not something that's going to end the next week or the next month,' said Alessandro Vespignani, a professor at Northeastern University.
He is part of a group of researchers that manages an online dashboard about the outbreak.
Epidemiologists have no crystal ball. They have only piecemeal information on the new virus, which appeared in December.
They use mathematical models to estimate the actual number of cases, as of the current date, and compare them to past outbreaks -- but many of their hypotheses remain uncertain.
Until the past weekend, researchers thought that infected people were not contagious until they began exhibiting symptoms, such as fever, respiratory problems, and pneumonia. But Chinese authorities said Sunday they had established the opposite.
US health authorities said Monday they had not seen evidence that asymptomatic patients can infect other people. But if they can, this would definitely change the outbreak's dynamics.
The first estimates for the length of the incubation period -- about two weeks -- are recent.
Children in Cambodia, which confirmed its first case of coronavirus yesterday, are now wearing face masks at school to stop the virus spreading. Schools in China are still closed
Many roads in China are being closely monitored – if not closed – by the authorities to stop people transporting the coronavirus around the country. Pictured today, January 28, a man is screened by officials at a checkpoint at the city of Yueyang, Hunan
A China Eastern check-in desk at Incheon International Airport in South Korea is pictured deserted today, January 28. Normally, the Lunar New Year period sees millions of people travel around the Far East to visit family
In recent days, multiple experts have calculated an important parameter for any outbreak: the basic reproduction number, or 'R0.' It represents the number of people contaminated by an infected person. Estimates range from 1.4 to 3.8, according to Fisman, figures that are considered moderate.
That is only an average: some patients may infect many people, while others infect only a few. 'On its own, it isn't a reason to panic,' said Maimuna Majumder, a researcher at Harvard University and at Boston Children's Hospital.
She said the rate is 1.3 for seasonal flu (which has millions of cases per year) and between two and five for Severe Acute Respiratory Syndrome (SARS), which resulted in 8,000 cases and 774 deaths, the majority in mainland China and Hong Kong in 2002-2003. In comparison, the rate for measles ranges from 12 to 18.
Quarantines and isolation measures, systematic hand washing and masks could help drive down the average number of infected people. If the rate falls below one, the epidemic will die down.
But the effect of the control measures China has implemented won't be felt for another week or two, researchers say, based on the virus's cycle.
'The more we learn about it, the more it looks like SARS,' said Fisman. 'SARS was controllable; hopefully this will be too. But we won't know for a few weeks.'
'It's going to be many weeks, probably months, and nobody knows where this will go,' he added.
The official number of cases is more than 4,000 in China, with more than 100 deaths, and some 50 confirmed infections outside the country.
But the actual number of Chinese cases, including those not yet detected, is likely to be more than 25,000, said Vespignani, according to the analysis of the group coordinated by Northeastern.
And researchers at the University of Hong Kong (HKU) estimate the number of actual cases has currently passed 40,000.
'It's easy to get to twice or three times as much, even just in the city of Wuhan,' the virus's epicenter, said Vespignani. 'If we start to have other larger areas affected, then those numbers are going to be much, much bigger.'
He said he doesn't want to estimate the number of possible deaths. The mortality rate, until now, has hovered around three percent, but rates tend to fluctuate: they increase at the beginning as the most vulnerable patients die, then drop, and then rise again as others die.
What do we know about the deadly coronavirus? What are the symptoms... and how worried SHOULD the world really be?
Someone who is infected with the Wuhan coronavirus can spread it with just a simple cough or a sneeze, scientists say.
Eighty-one people with the virus are now confirmed to have died and more than 2,800 have been infected in at least 11 countries. But experts predict the true number of people with the disease could be 100,000, or even as high as 350,000 in Wuhan alone, as they warn it may kill as many as two in 100 cases. Here's what we know so far:
What is the Wuhan coronavirus?
A coronavirus is a type of virus which can cause illness in animals and people. It is an RNA virus (RNA is a type of genetic material called ribonucleic acid), which means it breaks into cells inside the host of the virus and uses them to reproduce itself.
This coronavirus from Wuhan is one which has never been seen before this outbreak. It is currently named 2019-nCoV, and does not have a more detailed name because so little is known about it.
Dr Helena Maier, from the Pirbright Institute, said: 'Coronaviruses are a family of viruses that infect a wide range of different species including humans, cattle, pigs, chickens, dogs, cats and wild animals.
'Until this new coronavirus was identified, there were only six different coronaviruses known to infect humans. Four of these cause a mild common cold-type illness, but since 2002 there has been the emergence of two new coronaviruses that can infect humans and result in more severe disease (Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronaviruses).
'Coronaviruses are known to be able to occasionally jump from one species to another and that is what happened in the case of SARS, MERS and the new coronavirus. The animal origin of the new coronavirus is not yet known.'
The first human cases were publicly reported from the Chinese city of Wuhan, where approximately 11million people live, after medics first started seeing cases on December 31.
By January 8, 59 suspected cases had been reported and seven people were in critical condition. Tests were developed for the new virus and recorded cases started to surge.
The first person died that week and, by January 16, two were dead and 41 cases were confirmed. The next day, scientists predicted that 1,700 people had become infected, possibly up to 4,500.
Just a week after that, there had been more than 800 confirmed cases and those same scientists estimated that some 4,000 – possibly 9,700 – were infected in Wuhan alone. By that point, 26 people had died.
By January 27, more than 2,800 people were confirmed to have been infected, 82 had died, and estimates of the total number of cases ranged from 100,000 to 350,000 in Wuhan alone.
Where does the virus come from?
Nobody knows for sure. Coronaviruses in general tend to originate in animals – the similar SARS and MERS viruses are believed to have originated in civet cats and camels, respectively.
The first cases of the virus in Wuhan came from people visiting or working in a live animal market in the city, which has since been closed down for investigation.
Although the market is officially a seafood market, other dead and living animals were being sold there, including wolf cubs, salamanders, snakes, peacocks, porcupines and camel meat.
Bats are a prime suspect – researchers at the Chinese Academy of Sciences said in a recent statement: 'The Wuhan coronavirus' natural host could be bats… but between bats and humans there may be an unknown intermediate.'
And another scientific journal article has suggested the virus first infected snakes, which may then have transmitted it to people at the market in Wuhan.
Peking University researchers analysed the genes of the coronavirus and said they most closely matched viruses which are known to affect snakes. They said: 'Results derived from our evolutionary analysis suggest for the first time that snake is the most probable wildlife animal reservoir for the 2019-nCoV,' in the Journal of Medical Virology.
So far the fatalities are quite low. Why are health experts so worried about it?
Experts say the international community is concerned about the virus because so little is known about it and it appears to be spreading quickly.
It is similar to SARS, which infected 8,000 people and killed nearly 800 in an outbreak in Asia in 2003, in that it is a type of coronavirus which infects humans' lungs.
Another reason for concern is that nobody has any immunity to the virus because they've never encountered it before. This means it may be able to cause more damage than viruses we come across often, like the flu or common cold.
Speaking at a briefing in January, Oxford University professor, Dr Peter Horby, said: 'Novel viruses can spread much faster through the population than viruses which circulate all the time because we have no immunity to them.
WHAT ARE COUNTRIES DOING TO GET THEIR CITIZENS OUT OF CHINA?
British ex-pats and tourists stuck in Wuhan have begged officials to 'get us out of here', venting their frustrations at the Government's response so far.
About 300 Britons who live in the city are growing increasingly anxious after the number of virus cases soared by 50 per cent in just 24 hours.
They accused the UK of dithering as it emerged the US, France, Spain, Australia, Japan, Thailand and Sri lanka had already organised evacuations for its citizens.
France's health minister Agnes Buzyn said officials will put 'hundreds' of citizens on a direct flight to the country later in the week.
She said authorities were working on arranging a bus service to get the expats to the airport.
There are some 800 French citizens stranded in the Wuhan area.
She said French nationals will be held in quarantine for two weeks on arrival to stop the virus spreading on home soil.
French car manufacturer Peugeot Citroen, which has a factory in Wuhan, said it was moving foreign employees and their families by bus to be quarantined in another city.
The US State Department is organising a single flight out of Wuhan on Tuesday directly to San Francisco.
It said in the event there are not enough seats, priority will be given to to individuals 'at greater risk from coronavirus' - those already showing symptoms.
Officials invited US citizens with a valid passport to contact the embassy in Beijing.
Private citizens are expected to later repay the travel costs, the notice said.
It is reported that a Boeing 767 jet - that can carry around 230 passengers - will fly the citizens home.
There are roughly 1,000 Americans living in and around the Wuhan area.
The German government said it was 'considering a possible evacuation of all willing German citizens' from Wuhan.
On Monday January 27 it advised all citizens to avoid travelling to China at all unless the trip was necessary.
Japan said it planned to evacuate all of its citizens using chartered flights. It claimed it was in final discussions about the logistics with Chinese authorities.
Some 430 Japanese nationals reside in or near Wuhan.
The government is also considering evacuation by road from Hubei Province, and have Japanese nationals take flights home from other places, according to Japanese media.
Spain's foreign minister Arancha Gonzalez tweeted this morning that Spanish official are trying to evacuate 20 Spaniards stranded in Hubei province.
She did not provide further details.
The government is meeting today to discuss how to evacuate the 70 known expats living in Wuhan, most of whom are students.
Air force commander ACM Manat Wongwat said that up to four planes with medical staff are on stand-by to evacuate its citizens in the coming days.
Officials have applied for a chartered plane to be allowed to land at Wuhan airport and pick up 32 Sri Lankan students and their family members stranded in the outbreak's epicentre.
Its foreign office also said it was working to bring back all other citizens living in the wider Hubei province.
There are about 860 Sri Lankan students are in China.
Foreign Minister Marise Payne said her government is 'exploring all opportunities' to help with evacuation of a number of Australians reportedly in Wuhan.
There are thought to be a small number of citizens living in the central Chinese city.
India has asked China if it can make arrangements for its expats to leave.
It is not clear how and when India plans to evacuate its citizens if approval is granted. Around 250 Indians are still in Wuhan.
'Most seasonal flu viruses have a case fatality rate of less than one in 1,000 people. Here we're talking about a virus where we don't understand fully the severity spectrum but it's possible the case fatality rate could be as high as two per cent.'
If the death rate is truly two per cent, that means two out of every 100 patients who get it will die.
'My feeling is it's lower,' Dr Horby added. 'We're probably missing this iceberg of milder cases. But that's the current circumstance we're in.
'Two per cent case fatality rate is comparable to the Spanish Flu pandemic in 1918 so it is a significant concern globally.'
How does the virus spread?
The illness can spread between people just through coughs and sneezes, making it an extremely contagious infection. And it may also spread even before someone has symptoms.
It is believed to travel in the saliva and even through water in the eyes, therefore close contact, kissing, and sharing cutlery or utensils are all risky.
Originally, people were thought to be catching it from a live animal market in Wuhan city. But cases soon began to emerge in people who had never been there, which forced medics to realise it was spreading from person to person.
There is now evidence that it can spread third hand – to someone from a person who caught it from another person.
What does the virus do to you? What are the symptoms?
Once someone has caught the virus it may take between two and 14 days for them to show any symptoms – but they may still be contagious during this time.
If and when they do become ill, typical signs include a runny nose, a cough, sore throat and a fever (high temperature). The vast majority of patients – at least 97 per cent, based on available data – will recover from these without any issues or medical help.
In a small group of patients, who seem mainly to be the elderly or those with long-term illnesses, it can lead to pneumonia. Pneumonia is an infection in which the insides of the lungs swell up and fill with fluid. It makes it increasingly difficult to breathe and, if left untreated, can be fatal and suffocate people.
What have genetic tests revealed about the virus?
Scientists in China have recorded the genetic sequences of around 19 strains of the virus and released them to experts working around the world.
This allows others to study them, develop tests and potentially look into treating the illness they cause.
Examinations have revealed the coronavirus did not change much – changing is known as mutating – much during the early stages of its spread.
However, the director-general of China's Center for Disease Control and Prevention, Gao Fu, yesterday said the virus was mutating and adapting as it spread through people.
This means efforts to study the virus and to potentially control it may be made extra difficult because the virus might look different every time scientists analyse it.
More study may be able to reveal whether the virus first infected a small number of people then change and spread from them, or whether there were various versions of the virus coming from animals which have developed separately.
How dangerous is the virus?
The virus has so far killed 82 people out of a total of at least 2,800 officially confirmed cases – a death rate of around three per cent. This is a higher death rate than the Spanish Flu outbreak which, in 1918, went on to kill around 50million people.
However, experts say the true number of patients is likely considerably higher and therefore the death rate considerably lower. Imperial College London researchers estimate that there were 4,000 (up to 9,700) cases in Wuhan city alone up to January 18 – officially there were only 444 there to date. If cases are in fact 100 times more common than the official figures, the virus may be far less dangerous than currently believed.
Experts say it is likely only the most seriously ill patients are seeking help and are therefore recorded – the vast majority will have only mild, cold-like symptoms. For those whose conditions do become more severe, there is a risk of developing pneumonia which can destroy the lungs and kill you.
Can the virus be cured?
The Wuhan coronavirus cannot currently be cured and it is proving difficult to contain.
Antibiotics do not work against viruses, so they are out of the question. Antiviral drugs can, but the process of understanding a virus then developing and producing drugs to treat it would take years and huge amounts of money.
No vaccine exists for the coronavirus yet and it's not likely one will be developed in time to be of any use in this outbreak, for similar reasons to the above.
The National Institutes of Health in the US, and Baylor University in Waco, Texas, say they are working on a vaccine based on what they know about coronaviruses in general, using information from the SARS outbreak. But this may take a year or more to develop, according to Pharmaceutical Technology.
Currently, governments and health authorities are working to contain the virus and to care for patients who are sick and stop them infecting other people.
People who catch the illness are being quarantined in hospitals, where their symptoms can be treated and they will be away from the uninfected public.
And airports around the world are putting in place screening measures such as having doctors on-site, taking people's temperatures to check for fevers and using thermal screening to spot those who might be ill (infection causes a raised temperature).
However, it can take weeks for symptoms to appear, so there is only a small likelihood that patients will be spotted up in an airport.
Is this outbreak an epidemic or a pandemic?
The outbreak has not officially been confirmed as either an epidemic or a pandemic yet. This is likely because, despite the global concern, the number of people who have been confirmed to be infected is still relatively low.
A pandemic is defined by the World Health Organization as the 'worldwide spread of a new disease'.
An epidemic is when a disease takes hold of a smaller community, such as a single country, region or continent.