China's most populous city has locked down millions of its residents, again tightening the first phase of two-stage <a href="https://www.thenationalnews.com/tags/covid/" target="_blank">Covid-19</a> defences as the number of daily cases passed 4,400. On Tuesday, many residents in Shanghai were asked to stay at home unless they were going out for a coronavirus test. The city, which is <a href="https://www.thenationalnews.com/tags/china/" target="_blank">China</a>'s financial centre and has a population of 26 million people, is in its second day of a lockdown that splits it roughly along the line of the Huangpu River. It divides the historic centre from the eastern business and industrial district of Pudong to allow for staggered testing. While the Shanghai caseload remains modest by global standards – a record 4,381 asymptomatic cases and 96 symptomatic cases for March 28 – the city has become a testing ground for the country's “zero-Covid” strategy as it tries to bring the <a href="https://www.thenationalnews.com/uae/2022/03/25/what-is-the-new-covid-variant-ba2-and-are-the-symptoms-more-severe/" target="_blank">highly infectious Omicron variant</a> under control. Residents east of the Huangpu were initially locked down in housing compounds on Monday, but mostly allowed to move within the compounds. On Tuesday, however, two residents told Reuters they were informed by their neighbourhood committees they were no longer allowed to cross their doorsteps. “Children were still having picnics yesterday and having fun,” one said. Wu Qianyu, an official with the municipal health commission, told a press briefing on Tuesday that locked-down residents should not leave home, even to take pets for exercise or throw rubbish out. “This is in fact a key stage in nucleic acid testing, and we have made a clear request for people in locked down areas to stay home,” she said. She said 17,000 testing personnel from Shanghai and surrounding regions had set up 6,300 stations and conducted a total of 8.26 million tests in locked-down districts on Monday. “The vast numbers of medical staff, grass roots cadres, community workers and volunteers shared the very hard work on the front line of epidemic prevention and control and should be thanked,” she said. Drone footage published by Chinese state media showed empty streets surrounding the skyscrapers of the city's Lujiazui financial district in Pudong. Public transport in the east has been shut and all unapproved vehicles have been barred from roads. The Shanghai Stock Exchange, in the western part of the city, said it kept a skeleton staff in place within the bourse for positions such as trading and technical system operations, while others work from home. Residents in the west of the city continued to rush to grocery stores and vegetable markets to stock up in anticipation of the April 1 start date of their lockdown, with long queues and crowds. US hypermarket chain Costco said it was closing from Tuesday, before the area's scheduled lockdown, along with some gyms and shopping malls which also sit in Shanghai's western districts. The Shanghai government rolled out more measures to try to support coronavirus-affected businesses on Tuesday, including rent exemptions and billions of yuan in tax rebates.