(Bloomberg) — Beijing started mass testing millions of its residents as part of an unprecedented scheme designed to identify and squash omicron’s stealthy spread before it spirals out of control in the Chinese capital. 

Nearly 20 million people will undergo three rounds of Covid testing through the weekend as Beijing’s municipal government expands the effort that started in the eastern Chaoyang district, where most cases in the recent flareup have emerged. Ten other districts will be included in the testing, as well as an economic development area that houses JD Inc.’s headquarters and many other high-tech companies.

The scale of the program is unparalleled in Beijing, even as China has kept Covid in check since early 2020 thanks in large part to massive testing efforts that repeatedly spotted tiny incursions of the pathogen in the world’s most populous country. Beijing hopes to prevent this outcome from happening again. The more deadly omicron strain has penetrated several cities’ defenses and caused lockdowns such as the one in Shanghai. 

It is imperative to find out the extent of the omicron’s silent spread in this sprawling metropolis. On Monday, the city took control of parts of Chaoyang, which is home to many expatriates and most foreign embassies. Local leaders will be able to use the test results to determine how to identify the infected as well as those who have been exposed. 

The mass testing and Shanghai’s experience have caused jitters in Beijing about a potential wider lockdown, as such sweeping restrictions are now being implemented more frequently to control Covid outbreaks caused by the hyper-infectious omicron variants. China currently has more than 50 millions people under lockdown. 

The 25 million residents of Shanghai’s financial district are the most vulnerable. They have been held indefinitely without food and water for almost a month and faced severe health problems and shortages. There has been a growing outcry about the Covid Zero strategy’s harsh containment tactics. This approach was abandoned by most countries once the virus became endemic.

While Shanghai is seeing fewer daily infections than usual, it has seen a drop in the number of deaths. It dropped to 16,980 Monday, from 27,000 per day earlier. They reached nearly 200 as of Tuesday, mostly claiming the city’s elderly who have underlying ailments. 

©2022 Bloomberg L.P.