Life in much of the U.S. is returning to some semblance of normal following the winter COVID-19 wave, but China is ratcheting up its strict mitigation measures to quash its relatively small outbreak. Chinese authorities on Monday began a two-phase lockdown of Shanghai and its 26 million residents, starting with five days of requiring people in the Pudong financial district and surrounding areas to stay home until Friday as mass testing gets underway.

“Panic-buying was reported on Sunday, with supermarket shelves cleared of food, beverages, and household items,” The Associated Press reports. “Additional barriers were being erected in neighborhoods Monday, with workers in hazmat suits staffing checkpoints.”

Starting Friday, downtown Shanghai and other areas west of the Huangpu River will start a five-day lockdown. “This staggered approach means that half of the city will be able to remain open,” BBC News reports. “Shanghai’s public transport has been suspended and firms and factories in the city have been ordered to halt operations or work remotely,” though some factories in the suburbs are still expected to operate, even if workers have to stay confined on-site. 

This will be the largest lockdown China has undertaken during the pandemic, though it will shorter than the 76-day clampdown on Wuhan and its 11 million residents in the first phase of the COVID-19 outbreak. It will also be test of the costs and benefits of China’s “zero COVID” policy. The Shanghai lockdown aims to “curb the virus spread, protect people’s life and health, and achieve the dynamic zero-COVID target as soon as possible,” Shanghai’s COVID-19 prevention and control office said Sunday evening.

China on Sunday reported 1,219 new symptomatic COVID-19 cases, including 50 in Shanghai, and 4,996 asymptomatic cases, with about 3,450 of them in Shanghai. In all, China has reported 56,000 confirmed cases this month.  The outbreak is centered in Jilin province.