Behind the Collapse of Xi'an Covid-19 App

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January 4 was the deadline for the municipal government in Xi’an, the ancient capital of China with a population of 12 million, to reach its goal of zero new daily Covid-19 case. On January 1, there were 122 new infections; On January 2, the daily count fell to 90; On January 3, the figure was 95.The new cases in 24 hours were not many compared with thousands in many cosmopolitan regions in North America during