Countries like the US, Japan, and Thailand have confirmed cases.
And on Wednesday (January 22), a Chinese health official has said the virus is "adapting and mutating".
So what do we actually know about this flu-like virus?
Health officials now say it can be passed from person to person.
So far, hundreds of cases have been confirmed, and several people have died.
Symptoms include fever, coughing and difficulty breathing.
And can lead to pneumonia.
The exact origin is unknown.
Though Chinese officials have linked the outbreak to a seafood market in the city of Wuhan.
All of the deaths so far have been reported in that city in central China.
It's also home to a Foxconn plant which is a key supplier to Apple.
And it's hosting Olympic qualifiers for women's soccer next month.
Things to look out for next will be what happens over Chinese new year and whether fear takes its toll on the global economy.
Millions of people are preparing to travel around China and abroad for the new year celebrations, raising the risk of a wider contagion.
Fear of a pandemic has sent chills through the markets.
Investors are comparing it to China's 2003 SARS outbreak that killed nearly 800 people and by some estimates caused 40 billion dollars in global economic losses.
Aviation and luxury goods stocks have already been hit particularly hard.
With concerns it could deter Chinese consumers from traveling or shopping.
Health related companies though have seen their shares rise to dizzying heights.
One China-based biotech firm saw its shares rise more than 40 percent this week.