Starting from Monday, workplaces in Pudong New Area, Huangpu, Jing'an, Xuhui, Putuo, and Qingpu districts will require residents to provide negative COVID-19 test results taken any day from March 16 to 20, the city announced on Sunday.Multiple free nucleic acid tests have been carried out over the past few days in the city, and COVID-19 control measures have been stepped up such as promoting distance working.The city also calls for residents to reduce their unnecessary social gatherings and wear masks properly in public places.