Omicron Vs Zero-Covid: How Will China Exit Zero-Covid?

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China’s stringent zero-COVID strategy is likely to face its toughest test yet in the next few weeks, as millions of people travel around the country for Chinese New Year, and the Winter Olympics begin in Beijing, reports Nature.

Issue with Zero Covid 

The approach has been under pressure since China’s first Omicron cases were reported in mid-December. The highly infectious variant has been detected in at least 14 provinces and cities including Tianjin and Beijing, and scientists fear that fresh outbreaks might occur after next week’s events.

Even though Omicron is tough to contain, its increased transmissibility and ability to evade vaccine-derived immunity have hardened support for China’s unwavering strategy among some scientists.

Near-impossible to keep out

Researchers say that vaccines based on inactivated-virus technology — such as China’s widely used CoronaVac and Sinopharm vaccines — offer some protection against severe disease with Omicron, but will prevent few Omicron infections. “It is not the right time to reopen,” says Chen Tianmu, an epidemiologist at Xiamen University.

But other researchers argue that it will be near-impossible for China to keep the variant out. The costs of shutting borders outweigh the benefits, now that vaccines can reduce hospitalizations and deaths, he says. “It is getting harder and harder to justify the zero-COVID approach.”

In the past few months, China has experienced its largest COVID-19 outbreak since April 2020. In late November, daily cases of infections peaked at 361 — a marginal figure relative to the size of the country’s population. Nevertheless, in response, China’s government pursued swift and severe measures to get case numbers down.

Millions-strong cities have implemented strict lockdowns and introduced rounds of mass testing. Residents have had to make do with intermittent deliveries of food and medicines. 

Throughout the pandemic, China’s international borders have effectively been closed, preventing almost anyone from getting in or out. That has kept daily cases in the country in the hundreds or fewer, rather than the hundreds of thousands of daily cases recently seen in countries such as the United Kingdom and the United States.

Ineffective inactivated vaccines

This heavy-handed response continues even though China has administered nearly 3 billion doses of vaccines. Some 85% of the population have been fully vaccinated, and a large fraction have received a third dose.

But a highly vaccinated population is unlikely to be a barrier against Omicron’s spread. The relative inefficacy of China’s vaccines at preventing infections, combined with Omicron’s increased transmissibility, will make it harder for China to maintain its zero-COVID approach, says Yanzhong Huang. 

However, “it’s precisely that lack of confidence in their vaccines” that is causing China to stick to the zero-COVID approach, he adds.

Modelling led by Chen suggests that even with 80–90% coverage with its existing vaccines, China could still experience huge numbers of hospitalizations and deaths, if it relaxed its zero-tolerance strategy while a variant with similar properties to those of Omicron was spreading.

Fears about this kind of outcome have led China to double-down on its pandemic-response efforts, says Huang. The government is strongly urging people not to travel for Chinese New Year celebrations but it has stopped short of a total ban, so there is likely to be movement of people anyway.

Planning an exit

“We advise to push forward the boosters to combat the emerging variant,” says Pengfei Wang, a virologist at Fudan University in Shanghai.

Booster-vaccine coverage should be “as high as possible before we reopen the country”, reaching at least 90%, agrees Chen. “We need to build our immunity barrier high.”

Cowling argues that China should time the ramp-up of its booster campaign as close to the nation’s reopening as possible, to account for waning immunity. “Vaccines are not so critical for maintaining zero-COVID but are really critical for an exit from zero-COVID,” he says.

Furthermore, different kinds of vaccine — such as those based on mRNA, rather than inactivated-virus vaccines — should be considered for third, booster shots, says Lu Jiahai, an infectious-diseases epidemiologist at Sun Yat-sen University in Guangzhou, as this may offer better immunity.

Although the country’s inactivated-virus vaccines have been the most widely used, China has also approved an adenovirus-vector and a protein-subunit vaccine. Furthermore, it has two mRNA vaccines in early-stage trials, says Lu. 

Alternatives to inactivated-virus vaccines are more widely available internationally, but China has so far shown a dogged determination to use only Chinese jabs.

In December 2020, Shanghai-based pharmaceutical company Fosun Pharma and biotechnology company BioNTech, based in Mainz, Germany, announced that they had collaborated to produce an mRNA COVID-19 vaccine and to supply doses to China. However, the vaccine has not yet been approved by regulators. If it is, it would be the first internationally developed vaccine to be approved in mainland China.

Some researchers say that outbreaks during the Olympics might start to loosen the authorities’ zero-COVID approach, and contribute to a mental shift among the population towards a greater tolerance of outbreaks.

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Source: Nature

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