The spike in cases comes from the remote city of Kashgar in the northwestern Xinjiang region, where a 17-year-old teenager working in a garment factory tested positive on Saturday.
Despite her having no symptoms, the authorities decided to test all 4.75 million residents of the city, in a drive that returned 137 positive – but all asymptomatic – results on Sunday.
It was not clear how the teenager was infected, but all the other 831 workers at her factory tested negative. Authorities said all of the new cases on Sunday were linked to a single, different factory, the South China Morning Post reported.
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More than 2.84 million people in the Kashgar area had been tested as part of the drive as of Sunday afternoon, with the remaining tests expected to be completed by Tuesday. Schools in the city have been closed, and residents are not allowed to leave unless they can show a negative test result.
The outbreak is the biggest since a cluster of cases linked to a market in Beijing in June. The scale and speed of the testing is in line with those seen during other outbreaks in China, including in Qingdao earlier this month when the entire population of nine million people was tested. In May, China tested all 11 million residents of Wuhan, the city where the novel coronavirus was first identified, after detecting a small cluster of cases.
China has largely been successful in bringing infection rates down and getting life back to normal, but there continue to be small outbreaks, with a total of 20 new symptomatic and 161 new asymptomatic cases reported in the mainland on 25 October.
The total number of confirmed Covid-19 cases in mainland China to date now stands at 85,810, while the death toll remained unchanged at 4,634.
Additional reporting by agencies
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