The number of coronavirus cases in China's Hubei province dramatically jumped by 15,000 overnight. Here's why.

· China's Hubei province recorded a huge spike in the number of Wuhan coronavirus cases on Thursday, announcing almost 15,000 new cases and 242 additional deaths in just 24 hours.
· It is the largest single-day increase since the outbreak began. It came as the province — where the outbreak began — changed its methods of...