The previously unknown virus has set global alarm bells ringing as scientists scramble to map the outbreak and the new strain. Key elements, such as how do you know someone is contagious or the rate of infection, remain vague at best.
The 2019 novel coronavirus –– a virus similar to the SARS (Severe acute respiratory syndrome) pathogen –– has claimed more than 80 lives in China and infected thousands there and outside the country, despite unprecedented quarantines and travel lockdowns.
Here's what you need to know about the disease, also called the 2019-nCoV.
Did the virus spread from bats?
Videos of a woman eating soup with a whole bat seen in the bowl went viral last week, giving rise to the idea the new virus came from the winged mammals.
This coronavirus may have originated in bats, according to genetic analysis, but researchers say there could have been an "intermediate host" in the transmission to humans. One study in the Journal of Medical Virology suggests the coronavirus transferred from bats to snakes before it mutated further to infect humans.
No one is certain yet how the cold-blooded snakes passed on the disease to humans.
Gao Fu, director of the Chinese Center for Disease Control and Prevention, says the virus likely came from "wild animals at a seafood market" in central China's Wuhan city. Wuhan is considered ground zero of the novel coronavirus, from where it spread to nearly 3,000 confirmed cases nationwide.
However, scientists argue a new study suggests the virus may have come into the Wuhan market, infected a cluster in the market, before it spread from that cluster to other places.
The market –– now shut –– offered a range of exotic wildlife for sale, including live foxes, crocodiles, wolf pups, giant salamanders, snakes, rats, peacocks, porcupines, and camel meat. More investigation would be needed from samples from the market before conclusive answers on zoonosis.
SARS was linked to the Chinese consumption of civet meat.
How do you know if you have the virus?
The new virus comes from a large family of what are known as coronaviruses, some causing nothing worse than a cold.
WHO says the common signs of the novel coronavirus include respiratory symptoms, fever, cough, shortness of breath and breathing difficulties. In other words, it could present as a seasonal allergy or a regular cough.
Based on a study of 41 early-detected cases, patients did not present with runny noses, sneezing or sore throats.
Some of the new virus' symptoms resemble those of SARS, the Chinese scientists reported in The Lancet.
"There are some important differences," Bin Lao, the lead author of a Lancet study says.
The new virus did not cause stomach problems such as diarrhoea, which hit 20-25 percent of SARS patients.
In more severe cases, the new coronavirus can cause pneumonia, severe acute respiratory syndrome, kidney failure, and even death.
All patients studied developed pneumonia, most had a fever, three-quarters of them were coughing and more than half had trouble breathing.
The average age of the 41 patients studied was 49, most of them having visited Wuhan market, identified as the source of the outbreak. Nearly a third of them had serious breathing difficulties and six of them died.
All this gives us a preliminary sketch of the new virus, even if one has to be cautious about drawing conclusions based on such a small sample.
The study is all the more important because a current epidemic of flu, which has similar symptoms, has made isolating patients of the new virus difficult.
According to Arnaud Fontanet, head of the department of epidemiology at the Institut Pasteur in Paris, the new strain is the seventh known type of coronavirus that humans can contract.
Fontanet says the current virus strain is 80 percent genetically identical to SARS, which also causes severe breathing problems.
How is it spreading so far and so fast?
The incubation period –– the time between when a person first contracts a virus and when the symptoms first show –– for the new virus is thought two weeks. Chinese scientists said the virus is contagious even if the infected person has not started showing any symptoms.
That means an infected person could bypass all virus controls currently in place for around two weeks, infecting many others in their path.
It seems initial symptoms are mild – a person with the novel coronavirus could continue to travel undetected for some time, even a week after the incubation period. It is not yet clear if the virus follows the same pattern in all patients.
Nathalie MacDermott of King's College London said it is likely the virus is spreading through droplets in the air from sneezing or coughing.
Chinese scientists have also confirmed the virus is passing from person to person without any contact with the now-closed market.
How contagious is it?
Scientists at the University of Hong Kong (HKU) currently mapping the outbreak warned their latest models show the number of actual infections was likely to be much higher than the official tolls, which only account for those who have been found and have tested positive.
As many as 44,000 people may have been infected as of Saturday after evidence emerged suggesting people may be infectious even when they are not showing symptoms.
HKU team lead Gabriel Leung says the number of infections would likely double every six days, peaking in April and May for those places currently dealing with an outbreak, although effective public health measures could bring that rate down.
"The problem is that we still do not have enough data to accurately specify" the virus' basic reproduction number –– or level of infectiousness, says William Keevil of the University of Southampton in England.
But research still going through the peer review research process suggested that it might be "quite high" he says.
"So if this is confirmed and the virus were to mutate in future to a more dangerous form, this would be concerning," he said.
Very reassuring and not dystopian at all. The medical staff at the Wuhan People’s Hospital wishes everyone a happy new year and not to worry about the Coronavirus.— Ian Miles Cheong (@stillgray) January 26, 2020
Is there a vaccine to combat the novel coronavirus?
There is currently no vaccine to prevent 2019-nCoV infection, according to the Centers for Disease Control and Prevention, a US federal health agency.
The CDC said there is no specific antiviral treatment recommended for 2019-nCoV infection.
But China is testing an HIV drug as a treatment for symptoms of the new virus, drugmaker AbbVie Inc said.
China's health authorities requested the drug to help with the government's efforts to address the crisis, according to Adelle Infante, a spokeswoman for North Chicago, Illinois-based AbbVie.
Aluvia, which is also known as Kaletra, is a combination of lopinavir and ritonavir.
The Chinese government says there is no effective anti-virus medicine but suggested taking two lopinavir/ritonavir pills and inhaling a dose of nebulized alpha-interferon twice a day.
The US National Institutes of Health said it is in the "very preliminary stages" of research to develop a vaccine.
Drug company Regeneron –– which developed a treatment of Ebola –– also said it's in the early stages of designing a potential treatment for this coronavirus.
Italian health authorities don’t seem to be taking any chances with the coronavirus. Just landed in Milan from Hong Kong and every passenger is having their temperatures checked and providing contact details #WuhanCoronavirus pic.twitter.com/GARa7C3hCG— Britt Clennett (@BrittClennett) January 27, 2020
How can you stay safe?
Health authorities and scientists suggest the same precautions used against other viral illnesses: wash your hands frequently, cover up your coughs, try not to touch your face or others.
And anyone who does come down with the virus should be placed in isolation.
According to the WHO, 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.