The city of Wuhan, China, was placed under a lockdown on January 23, leaving around 11 million people quarantined in the epicenter of the virus.

China cut off transport links inside and outside the city to try and stop the virus, and ordered places like cinemas and cafes to close.

The World Health Organization called cutting off a city as large as Wuhan "unprecedented in public health history," and said it isn't sure if the strategy will work.

China later extended the measures to other cities, covering around 60 million people, creating what is thought to be the largest quarantine in human history.