For most, the disease is mild, but some people die.
So how is the virus attacking the body, why are some people being killed and how is it treated?
This is when the virus is establishing itself.
Viruses work by getting inside the cells your body is made of and then hijacking them.
The coronavirus, officially called Sars-CoV-2, can invade your body when you breathe it in (after someone coughs nearby) or you touch a contaminated surface and then your face.
It first infects the cells lining your throat, airways and lungs and turns them into “coronavirus factories” that spew out huge numbers of new viruses that go on to infect yet more cells.
At this early stage, you will not be sick and some people may never develop symptoms.
The incubation period, the time between infection and first symptoms appearing, varies widely, but is five days on average.