The plans of Chinese cities hit by COVID-19 to exit or avoid lockdown are more fraught and uncertain than ever, as the search for zero cases grows more prolonged, taxing and complex, with the highly contagious omicron variant demanding quicker and tougher action.

The lockdowns have led the World Health Organization's (WHO) chief to describe China's zero-COVID-19 goal as unsustainable, but China says its approach will protect the lives of its people and economy in the long run.

With one week of "slow living" in March, the city of Shenzhen had one of the shortest lockdowns among COVID-19-hit cities with populations of more than 10 million. Its decision on citywide testing and mobility curbs was made when caseloads rebounded in mid-March following less disruptive measures earlier in an outbreak that began in February.

Between March 14 and March 20, about 20 million residents underwent multiple rounds of testing and largely stayed at home, with one member of each household allowed out every few days for necessities. Buses and subways were shut down and nonessential businesses were halted, while work from home or sealed campuses were implemented. It was softer than the hard Wuhan lockdown in 2020; residents could leave Shenzhen if they had negative PCR tests and private transport was not banned.

Shenzhen largely achieved zero community cases after seven days of lockdown.

Shanghai misery

The twin outbreaks in Beijing and Shanghai, the country's most prominent cities, have focused attention on whether China can sustain its strict "zero-COVID-19" approach, as many other countries adapt to the fast-spreading omicron variant and ease restrictions.

Unlike Shenzhen's swift lockdown, Shanghai initially refrained from a blanket closure. In the first few weeks of its outbreak, the city of 25 million stuck to a "slicing and gridding" policy in which residential compounds and areas took turns sealing up and administering mass testing. By the end of March, Shanghai was reporting more than 600,000 cases since early March, leaving authorities with no choice but to seal off the entire city in an unprecedented lockdown that sparked anger over poor access to medical services and daily necessities, fuelled criticism of opaque information disclosures and dealt a huge blow to the city's economy.

Shanghai on April 11 started identifying areas with no infections for at least 14 days and pledged to allow their residents limited mobility, but many complained that in practice they were still confined in residential compounds. In mid-May, Shanghai said it had zero transmissions outside quarantine areas and restarted some in-person businesses. Full resumption is expected in June, after two months of lockdown.

The Beijing method

Authorities in Beijing restricted more residents to their homes on Tuesday in a now three-week effort to control a small but persistent COVID-19 outbreak in the Chinese capital.

Beijing, nearly a month into its outbreak, has avoided a Shanghai-style lockdown, having acted quickly even when caseloads were very low. Three days into its outbreak, Beijing launched mass testing in its most populous district and immediately expanded that to most of its 21 million population. It also locked down selected areas with infections.

As Beijing's caseload grew, some residents were advised not to cross district boundaries and to work from home. Public transport, taxi and ride hailing services were reduced.

Still, Beijing stopped short of keeping all residents indoors. Nor did it restrict how often people could go out to shop for necessities.

Jilin lockdown

Jilin in northeast China banned people from leaving the province or from travel between its cities for nonessential reasons on March 14.

The large-scale travel curb was the first since 2020 when cities in central Hubei province cut off transport routes after the emergence of COVID-19 in Wuhan, Hubei's capital. In late April, daily cases in Jilin dropped to fewer than 100 on some days from a few thousand. Community infections hit zero on April 14.

Meanwhile, some border towns have faced repeated outbreaks and lockdowns such as Ruili, China's gateway to Myanmar, and Manzhouli in the north.

China has demanded more stringent measures in border towns, being the first line of defense against imported infections. Maguan, next to Vietnam, lifted a lockdown this month after achieving zero cases in an outbreak of about 200 infections, but tough rules remained indefinitely in some areas including bans on travel without permission.