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The coronavirus that emerged in Wuhan, China, in December 2019 has infected thousands of people and triggered alarm around the world. Here's what is known:
• Coronaviruses are a family of viruses that get their name from what they look like under a microscope - they are spherical and their surfaces are covered with "crown"-like spikes.
• Coronavirus infections have a wide range of symptoms, including fever, coughing, shortness of breath and breathing difficulties. Mild cases can cause cold-like symptoms, while severe cases can cause pneumonia, severe acute respiratory illness, kidney failure and death.
• Like other coronaviruses, the newly identified China coronavirus is being transmitted from person-to-person via droplets when an infected person breathes out, coughs or sneezes. It can also spread via contaminated surfaces such as door handles or railings.
• Infection with the newly identified virus has an incubation period of between one and 14 days, and there are limited accounts that it may also be spreading before symptoms show.
• Infectious disease and virus specialists say the scale of the current outbreak now points to "self-sustaining" human-to-human transmission. They estimate that each infected person is infecting, on average, two to three more people.
• Animal viruses can mutate or combine with other viruses to create new strains capable of being passed to people. Scientists say the new coronavirus originated in bats and then passed to humans, possibly via an intermediary animal species.
• Genetic data suggest the new coronavirus is the result of viral recombination - a process where more than one virus infects the same cell at the same time and creates a "recombinant" virus strain.