About 16 million residents in Shanghai are being tested for the coronavirus during the second stage of the lockdown that shifted Friday to the western half of China’s biggest city and financial capital. Meanwhile, residents of Shanghai’s eastern districts who were supposed to be released from four days of isolation have been told their lockdowns could be extended if COVID-19 cases are found in their residential compounds. The lockdown in Shanghai, being done in two phases over eight days to enable testing of its entire population, has shaken global markets worried about the possible economic impact. China’s manufacturing activity fell to a five-month low in March, a monthly survey showed Thursday, as lockdowns and other restrictions forced factories to suspend production. For four days starting Friday, residents of Puxi on the west side of the Huangpu River dividing Shanghai cannot leave their neighborhoods or housing compounds. […]