An outbreak of pneumonia-like illnesses began in Wuhan, China, at the end of 2019.
Its symptoms are typically a fever, cough and trouble breathing, but some patients have developed pneumonia, a potentially life-threatening infection that causes inflammation of the small air sacs in the lungs.
Scientists in China recognised its similarity to two viruses that turned into global killers: SARS and MERS.
SARS, or severe acute respiratory syndrome, is caused by the SARS coronavirus, known as SARS Co, and first emerged in China in 2002.
By the end of the outbreak, the virus had spread to several other Asian countries as well as the UK and Canada, killing 774.
MERS, or Middle East Respirator Syndrome, originated in the region for which it's named, ultimately killed 787 people and belongs to the same family of coronaviruses as SARS.
The new virus wasn't a match for either of those two, but it did belong to the same coronavirus family.