The mysterious outbreak of pneumonia was first reported in Wuhan, central China's Hubei Province, in December 2019. Experts attributed the outbreak to a new strain of coronavirus, which then spread across China and abroad. 

Here is what we know so far:

- Confirmed cases: At least 574 in China, seven abroad

- Deaths: 17, all in Hubei Province

- Human-to-human transmission confirmed

- Health experts say virus has potential to mutate