The remote city of Kashgar in China’s far west detected more than 100 asymptomatic Covid-19 cases on Sunday, the regional health authority said.
Gu Yingsu, the Xinjiang health committee deputy head, told a press conference that all 137 new cases were related to one identified in a 17-year-old villager in Shufu county the previous day.
Gu said the cases were all related to a factory in a neighboring village where the girl’s parents worked.
The outbreak is the biggest reported in China since a cluster of cases linked to a market in Beijing in June.
The Kashgar authorities started a mass testing program after the girl was found to be infected during a routine screening. The health authority said the 17-year-old worked in a different factory making clothes and returned home once every two weeks. The 831 other workers at the girl’s factory all tested negative.