In a vivid report from Wuhan, population 11 million, our correspondent describes how nervous residents are buying up face masks and flooding hospitals to report fevers and coughs. He also explains why President Xi Jinping, who is eager to expand China’s global influence, is under pressure to show that the world’s most populous nation can responsibly handle a public health crisis.

Details: The outbreak has already killed at least nine and infected more than 400 people in China, and spread to at least five other countries, including the United States. The virus is thought to have originated with animals but is now spreading from person to person.

What’s next: The worry is that the outbreak will ripple farther across Asia as many people there travel for the weeklong Lunar New Year holiday that begins on Friday, and possibly turn into a pandemic.

Background: China withheld information during a 2002-2003 outbreak of another coronavirus, SARS, that killed more than 800 people. Mr. Xi’s authoritarian government has vowed to do better this time, but it’s already controlling the narrative about the virus by censoring news articles and social media posts.

Go deeper: Our graphics editor mapped where cases have been reported so far. Others have most likely gone unreported.