Medical workers sitting on a mobile sampling vehicle conduct COVID-19 nuclei acid tests for residents in Zhengzhou, China.

Health-care workers conduct COVID-19 tests in Zhengzhou, central China.Credit: Ma Jian/VCG via Getty

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.

The approach — which was introduced by the central government early in the pandemic and has involved large-scale lockdowns, mass testing and international travel bans — 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.

“Omicron is going to create more of a challenge and lead to more disruptions than previous variants,” says Ben Cowling, an epidemiologist at the University of Hong Kong. Outbreaks might spill into the community and will be difficult to control, he says. “The Olympics is going to be a big test.”

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. “You can’t stop the wind with your hand,” says Rafael Araos, a physician and epidemiologist at the University for Development in Santiago. 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. In Xi’an in December, the government even banned all traffic and cancelled flights.

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 seen in the past few weeks in countries such as the United Kingdom and the United States.

Officials wearing personal protective equipment wait to validate Olympic accreditation for people arriving at Beijing's airport.

Officials wait to process arrivals for the Olympics at Beijing airport.Credit: Carl Court/Getty

Ineffective inactivated vaccines

The 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, who studies global health in China at the Council on Foreign Relations in New York City. 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 relaxes its zero-tolerance strategy while a variant with similar properties to those of Omicron is 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 — which normally see huge numbers travelling across the country to visit family — but it has stopped short of a total ban, so there is likely to be movement anyway.

And international athletes attending the Olympics will be confined to a ‘bubble’, flying in on chartered flights, travelling from their hotels to sports venues in dedicated vehicles and being subjected to daily testing. Tickets will not be sold for events, and the few spectators who are allowed to attend will be instructed not to shout or cheer. In terms of precautionary measures, it’s probably “the most stringent Olympics in history”, says Huang.

Planning an exit

Researchers have differing views on when and how China might plan its exit from the zero-COVID strategy.

Many say ramping up booster campaigns is important. “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 messenger RNA, rather than inactivated-virus vaccines — should be considered for third, booster shots, because this might offer better immunity, says Lu Jiahai, an infectious-diseases epidemiologist at Sun Yat-sen University in Guangzhou.

A woman and child wear protective masks as they walk by mascot Bing Dwen Dwen outside the Beijing 2022 Winter Olympics "bubble".

Few people in Beijing have access to the Winter Olympics 'bubble', to which the athletes are confined.Credit: Kevin Frayer/Getty

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 steadfast 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 on the Chinese mainland.

But Shibo Jiang, a virologist at Fudan University, says it’s likely that none of the world’s available COVID-19 vaccines will offer sufficient protection against emerging variants. Instead, says Jiang, countries need to develop vaccines that can elicit potent neutralizing antibodies against the broader group of related coronaviruses. He adds that people in China are increasingly convinced of the need to invest in such vaccines, especially since the emergence of Omicron.

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.

But unless COVID-19 comes under control in the rest of the world, “as long as you believe that even a small opening can be devastating for China, you’re not going to expect it to abandon that approach”, says Huang. “There are some tough decisions for the leaders to make.”