The regional outbreak of COVID-19 cases in Kashgar Prefecture in northwest China's Xinjiang Uygur Autonomous Region was caused by a contaminated container from aboard, Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention said on Wednesday. 

Speaking at the Caijing Annual Conference, Wu also revealed that an investigation has found that the "patient zero" from Kashgar's cases was a male loader, who was asymptomatic at the time. 

"He unintentionally passed the virus to his wife, and his wife passed it to her mother and then her sister. The virus was eventually brought to a local factory which led to the regional outbreak," Wu said, adding that an asymptomatic virus carrier could ignite an outbreak. 

On October 24, Kashgar reported one asymptomatic case of COVID-19 and rolled out mass virus testing.

Following the testing, a total of 78 confirmed cases and 352 asymptomatic cases were found in Xinjiang, mostly in Kashgar. 

As of last Friday, all of them have been discharged, or released from medical observation.