Shanghai carried out another round of mass COVID-19 testing on Saturday, this time testing residents at least twice in a single day, as a city official in China’s financial hub acknowledged shortcomings in the handling of the outbreak. It was the fourth consecutive day of city-wide testing in Shanghai, which reported a record 23,600 new locally transmitted cases. While those case numbers are small by global standards, the city has become a testbed for the country’s elimination strategy, which seeks to test, trace and centrally quarantine all positive COVID cases. Beijing intervened after the failure of Shanghai’s initial effort to isolate the virus by locking it down in stages, insisting that the country sticks to its zero-tolerance policy to prevent its medical system from being overwhelmed. But the curbs have sharply squeezed supplies of food and other essential goods for the city of 26 […]