Mapping app location data shows how virus spread in China

For weeks after the first reports of a mysterious new virus in Wuhan, millions of people poured out of the central Chinese city, cramming onto buses, trains and planes as the first wave of China's great Lunar New Year migration broke across the nation. Some carried with them the new virus that has since claimed over 8 00 lives and sickened more than 37,000 people.

Officials finally began to seal the borders on January 23. But it was too late. Speaking to reporters a few days after the the city was put under quarantine, the mayor estimated that 5 million people had already left.

Where did they go?
"It's definitely too late," said Jin Dong-Yan, a molecular virologist at Hong Kong University's School of Biomedical Sciences. Five million out. That's a big challenge. Many of them may not come back to Wuhan but hang around somewhere else. To control this outbreak, we have to deal with this. On one hand, we need to identify them. On the other hand, we need to address the issue of stigma and discrimination."
He added that the initial spread of travellers to provinces in central China with large pools of migrant workers and relatively weaker health care systems "puts a big burden on the hospitals ... of these resource-limited provinces."