The most extensive travel restrictions to stop an outbreak in human history haven’t been enough. We analyzed the movements of hundreds of millions of people to show why.
It seems simple: Stop travel, stop the virus from spreading around the world.
Here’s why that didn’t work.
Many of the first known cases clustered around a seafood market in Wuhan, China, a city of 11 million and a transportation hub.
With each patient infecting two or three others on average, even a perfect response may not have contained the spread.
But Chinese officials did not alert the public to the risks in December. It wasn’t until Dec. 31 that they alerted the World Health Organization and released a statement.
The timing of the outbreak could not have been worse. Hundreds of millions of people were about to travel back to their hometowns for the Lunar New Year.
It was only at the end of January that Wuhan was placed under a lockdown and airlines started canceling flights. By Jan. 31, when the United States announced it would shut down entry from China for non-Americans, travel out of Wuhan had basically stopped.
It was too late. Outbreaks were already growing in over 30 cities across 26 countries, most seeded by travelers from Wuhan.