Shanghai is currently experiencing its worst COVID-19 outbreak since the pandemic started in early 2020. The megacity, with over 24 million residents, reports hundreds of confirmed locally transmitted cases and thousands of asymptomatic carriers everyday. Authorities have implemented the lockdown in two phases from March 28 to April 5, first targeting the eastern part of the Huangpu River, followed by the west. About 3,500 health care workers from neighboring Zhejiang and Jiangsu provinces have come to assist in conducting mass nucleic acid tests.