(Yicai Global) Nov. 26 -- The origin of a coronavirus outbreak in Kashgar in China's western Xinjiang Autonomous Region a month ago was traced to a shipping container from overseas, according to an official with the Chinese Center for Disease Control and Prevention.

Officials investigated after the outbreak and finally found patient zero, a cargo loader with no Covid-19 symptoms, the Paper reported CCDC Chief Epidemiologist Wu Zunyou as saying at the Caijing Annual Conference 2021 yesterday.

The worker passed the virus to family members, who then carried it to a factory, Wu said, from where it spread to the wider community.

Kashgar is an important gateway for China to the West. After the first Covid-19 infection was found there on Oct. 24, a total of 57 confirmed cases and 298 asymptomatic cases were detected by Nov. 9. As a result of effective prevention and control measures, the epidemic was quickly brought under control.

“Generally speaking, the amount of virus transmitted from object to person is small, and most of the infected people are mild and asymptomatic cases,” Wu said. “But in the case of human-to-human transmission, the amount of virus is usually larger, and transmission efficiency is higher.”

Everything becomes a cold chain when temperatures drop below zero in winter, he said, adding that it becomes more difficult to prevent an epidemic as more substances are able to act as virus vectors.

Wu also said that the ability of asymptomatic people to spread the virus is limited in an epidemic or pandemic. But they may become the trigger of an outbreak when there is no epidemic.