China placed all 17 million residents in one of its biggest cities under lockdown on Sunday, as virus cases doubled nationwide to nearly 3,400 and anxiety mounted over the resilience of its 'zero-Covid' approach in the face of the worst outbreak in two years.

The southern tech hub of Shenzhen told all residents to stay at home as the city struggles to eradicate an Omicron flare-up linked to neighbouring virus-ravaged Hong Kong.

The lockdown and a suspension of public transport will last until March 20, a city government notice said, adding that it would launch three rounds of mass testing.

The move extends an earlier lockdown imposed on the city's central business district.

Shenzhen reported 66 new infections on Sunday — a fraction of the 32,430 confirmed the same day in Hong Kong.

"If prevention and control is not strengthened in a timely and decisive manner, it could easily become large-scale community transmission," Shenzhen health official Lin Hancheng said at a briefing.

The surge in infections across China has also prompted authorities to close schools in Shanghai and lock down multiple northeastern cities, as 18 provinces battle clusters of the Omicron and Delta variants.

China, where the virus was first detected in late 2019, has maintained a strict 'zero-Covid' policy enforced with swift lockdowns, travel restrictions and mass testing when clusters have emerged.

But the latest flare-up, driven by the highly transmissible Omicron variant and a spike in asymptomatic cases, is testing that approach.

Shanghai has so far been spared a citywide order to stay home, but individual housing compounds were being locked down as the megacity ramped up efforts to contain infections and test suspected close contacts.

Jilin — the city at the centre of the outbreak in the northeast — was partially locked down Saturday, while residents of Yanji, an urban area of nearly 700,000 bordering North Korea, were also confined to their homes Sunday.

Zhang Yan, a Jilin health commission official, said the response from local authorities had been lacking.

"There is insufficient understanding of the characteristics of the Omicron variant… and judgment has been inaccurate," he said at a Sunday press briefing.

The neighbouring city of Changchun — an industrial base of nine million people — was locked down Friday, while at least three other small cities have been locked down since March 1.

The mayor of Jilin and the head of the Changchun health commission were dismissed from their jobs Saturday, state media reported, in a sign of the pressure placed on local authorities to contain virus clusters.

– Covid-zero? –

But the strain is showing, with officials increasingly urging softer and more targeted measures, while economists warn tough clampdowns are hurting the economy.

Some people in Shanghai housing compounds that have been locked down were told by authorities that the restrictions will last two days. Some schools, businesses, restaurants and malls have also been closed over close-contact fears.

Authorities also said Sunday that people cannot leave or enter Shanghai without a negative test taken in the past 48 hours.

"I have friends who I hung out with a few days ago but were suddenly quarantined recently," Shanghai resident Serena Li told AFP.

Long lines were seen outside hospitals as people rushed to get tested.

"There's no other way. We definitely have to do what the government has arranged," said a data analytics worker surnamed Zhang.

Shenzhen residents told AFP earlier Sunday that they were nervous about the renewed outbreak and draconian measures that may be used to tackle it.

"It's the worst since 2020," a resident surnamed Zhang said.

"The closures are too sudden, my friend woke up in the morning to find her building was sealed overnight without warning. Her boss had to mail her laptop to her."

The city, which has a large population of migrant workers, shares a land border crossing with Hong Kong — where the caseload over recent weeks has soared, alarming officials in Beijing.

Hong Kong currently has one of the world's highest death rates from the virus, as the Omicron variant cuts through its elderly population among whom vaccine hesitancy proliferates.

As cases rise, China's National Health Commission announced Friday that it would make rapid antigen tests available for citizens to buy online or from clinics for "self-testing".

Although nucleic acid tests will continue to be the main method of testing, the move suggests China may be anticipating that official efforts will not be able to contain the virus.

As virus cases surge, can China's zero-Covid strategy hold?
Beijing (AFP) March 14, 2022 –

China, the country where the coronavirus was first detected in 2019, is among the last remaining devotees to a zero-Covid approach to the pandemic.

But after two years of virtually closed borders, mass testing, targeted lockdowns and quarantines, the strategy is being stress-tested like never before as cases surge across the country.

With millions currently under lockdown, can China's approach hold out against the march of the Omicron variant?

What is zero-Covid?

China essentially closed itself off from the world in March 2020 to follow a formula it calls "dynamic zero" for curbing outbreaks: strict lockdowns and immediate mass testing.

Unlike during softer lockdowns elsewhere, people in China can be banned from leaving their building or forced to remain inside a hotel room if they are considered high-risk contacts.

Mandatory track-and-trace apps mean close contacts are usually detected and quarantined quickly.

Shops, schools, tourist sites, office blocks and malls have been summarily locked down with people inside after the detection of a single close contact.

Officials are routinely dismissed or castigated in state media for outbreaks in their areas. That puts the onus on local authorities to move fast and hard on any clusters.

Residents are forced to stay at home at a moment's notice, including the 17 million people of Shenzhen who were locked down on Sunday.

International flight volumes have also collapsed, with the limited arrivals undergoing strict weeks-long quarantine.

The government has said it will not renew expiring Chinese passports unless the holder has a good reason for travel — shredding outbound demand for travel.

Why has China held on?

China's caseload since the start of the pandemic — just over 115,000 — is a fraction of those recorded elsewhere.

The official death toll has stayed under 5,000.

Although cases from the chaotic initial outbreak in Wuhan in early 2020 are widely believed to have been under-reported, life since then has largely returned to normal.

Beijing's communist leadership has made its handling of the pandemic a matter of political capital, saying the low death rate demonstrates the strength of its governance model.

It has highlighted chaotic Covid responses in the US as an example of the wider failures of liberal democracies. Analysts warn any change in strategy will also need to shift perceptions of the virus among the masses in China.

Loosening virus restrictions could also prove risky for President Xi Jinping as he seeks a third term in October after billing himself as the leader who keeps China safe.

What is the impact?

Zero-Covid comes at a cost, both human and economic.

It has caused repeated disruption, particularly in port cities and border areas that endure almost constant lockdowns.

Analysts say repeated shutdowns of factories and businesses have contributed to the slowing economy.

And there has been a grinding impact on ordinary lives.

Locked-down communities have complained of poor access to food, supplies and medical treatment.

The distressing case of a pregnant Chinese woman miscarrying after a strict lockdown delayed her access to medical treatment reignited debate over the limits of China's zero-tolerance approach.

Meanwhile, migrant workers have been left stranded from families for months due to onerous travel rules and restrictions.

Examples of extreme enforcement have sparked outrage, such as when health workers beat a corgi to death after the owners were sent to quarantine.

Can it be maintained?

A top Chinese scientist said this month that the country should aim to coexist with the virus. Meanwhile, the government announced it was introducing rapid antigen tests for the first time, which would allow at-home testing — a potential loosening of the state's hold on the health crisis.

However, there are concerns over the capacity of the country's healthcare system and the efficacy of domestic vaccines.

Peking University researchers have warned China could suffer a "colossal outbreak" that would overwhelm its medical system if it relaxed restrictions to a similar level as in Europe and the US.

And officials are anxiously watching the experience of Hong Kong, where hospitals have struggled in a recent outbreak.

The city currently has one of the world's highest death rates from the virus, as the Omicron variant cuts through its elderly population, among whom vaccine hesitancy is common.