Experts: China could face tsunami of Covid cases if it relaxes policy - STAT

As the world watches the rare spectacle of protesters challenging China's authoritarian leadership over its increasingly perplexing "zero Covid" policy, people who study the disease see threats ahead for China — and beyond.

The zero Covid policy, which has kept cases and deaths in China to negligible numbers throughout the pandemic, seems doomed to fail in the face of the highly transmissible Omicron variant of the SARS-CoV-2 virus, they believe. But the Chinese leadership does not appear to be mapping a path to a safe exit ramp, leaving experts worried the country could see a tsunami of cases that would swamp its health care system if the national containment effort collapses.

"I think they're very poorly prepared and based on what we have seen in Hong Kong — which is probably the best proxy for what might happen in China — this could be fairly devastating," Francois Balloux, director of the University College London's Genetics Institute, told STAT in an interview.

Hong Kong similarly adopted a zero Covid policy, employing draconian quarantine, tracing, and testing policies to try to stop transmission of the virus. For more than two years, that system protected the city from the disease. But in the spring, Omicron breached Hong Kong, dramatically spiking the number of infections there.

The same pattern could play out in mainland China, said Ben Cowling, an infectious diseases epidemiologist at the University of Hong Kong.

"If it's not stopped, we'll see a lot of infections in those cities that have outbreaks. It will be like Hong Kong's experience earlier this year, where we had half the population infected within the space of about a month or two," he said.

Cowling was on a panel discussion on a podcast Monday night on the evolving events in China. One of the Chinese panelists was very bullish about zero Covid, arguing it had kept China from experiencing the losses countries like the United States have endured. China has recorded just over 5,2oo deaths from Covid since the start of the pandemic; the United States has recorded more than 1 million.

"I wanted to ask: How much would you pay for zero Covid? Because the price tag is going up and up and up," Cowling said. "A year ago it made a lot of sense. I think it was a very cost-effective strategy in China, just as it was in Singapore. But … it gets more and more difficult to sustain, and there's got to be a point where you start thinking the cost is no longer justified, or you run out of money to pay for it."

A number of countries — Australia, New Zealand, and Singapore among them — also adopted a zero Covid policy earlier in the pandemic, limiting entry to people who had quarantined and tested negative for the disease. But most of the zero Covid nations used the policy to buy time until vaccines were developed and deployed. Once their populations were protected, they transitioned out of the restrictive policies.

China, however, appears to believe it can fend off the virus indefinitely. With cases mounting to hitherto unseen levels — about 40,000 a day for the past several days — experts who have tracked the virus' trajectory through the rest of the world shake their heads at what they see as an unattainable goal.

Marion Koopmans, a virologist and head of the department of viroscience at Erasmus Medical Center in Rotterdam, the Netherlands, worried that the protests will further fuel the spread of Covid in China.

"The cat will be out of the box," Koopmans said. "That could then lead to — depending on what China does, how China responds — but it could lead to a very big wave, if this is no longer controllable."

Amplifying the concern of people like Koopmans is the state of immunity in the Chinese population. The country rapidly developed a number of vaccines, though it has leaned predominantly on inactivated vaccines, which use all or parts of killed viruses to trigger an immune response. These vaccines work, but are not thought to be as potent as the messenger RNA vaccines most Western countries have relied on.

Cowling said three doses of the inactivated vaccines — made by Sinovac and Sinopharm — protect pretty well against severe infection and death. But while a high percentage of people have had a primary series, which consists of two shots, only about half the country is estimated to have had a third. Booster shot uptake in older adults is low and many who have received a third shot did so nine months or a year ago, which suggests their protection may be waning, Balloux said. He suggested the government should strive to drive up immunity levels, especially among the elderly.

And paradoxically, the very fact that Chinese authorities protected their people from Covid for so long now renders them more vulnerable to the disease.

In countries where Covid has spread largely unchecked since vaccines were rolled out, many people have developed what's known as hybrid immunity. In addition to having been exposed to three, four, even five doses of vaccine, their immune systems have encountered the SARS-2 virus, expanding the breadth of their immunological defenses. Few people in China have the added protection that vaccination plus infection generates.

"There'll be some protection. It wouldn't be like 2020 in some parts of the world," Cowling said of what would happen if China cannot contain the infection. "But there would be a lot of severe cases, unfortunately … and China doesn't have a very robust health care system to manage large numbers of severe cases."

Even though the Omicron strain of the virus is less severe than say the Delta variant that preceded it, it is more infectious. With so many susceptible people, the number of cases could be massive.

Some people are openly speculating that having SARS-2 cycling through so many more people could fuel the emergence of new variants with even greater capacity to evade built-up immunity than the various Omicron subvariants have.

Koopmans thought it was a possibility. "It's a whole new chapter, and a wildcard chapter potentially unrolling," she said. She noted, though, that the lack of broad immunity in China might work against that happening, given that one of the principal triggers of viral evolution is the virus' need to acquire ways to evade human immunity.

"The positive, if you can call it that, is that if there is not that much of an immunity wall, then there's not that much selection pressure [on the virus]," Koopmans said. "So that might work against further variant selection."

Cowling also noted that there is plenty of ongoing SARS-2 circulation elsewhere that could spark the emergence of new variants.

Viral evolution isn't the only threat, though, that a failure of the zero Covid policy — or the lack of a controlled exit — could pose. The supply chain issues that have dogged the world through the pandemic could be exacerbated if China faces a major wave of Covid.

A number of large companies are having major challenges with Chinese supplies already, "and this could only make things much worse," said Michael Osterholm, the director of the University of Minnesota's Center for Infectious Disease Research and Policy, which has a program in which experts liaise with companies on the implications of infectious diseases outbreaks.

China is a major producer of drugs and a major exporter of key ingredients of drugs. Osterholm, who has been studying supply chain vulnerabilities for years, said of 153 vital drugs used in the United States, all are made either in China or are reliant on active pharmaceutical ingredients sourced from China.

He, too, worries about how China is going to find a solution to its zero Covid dilemma, suggesting the leadership may be taking too much comfort from how well the country weathered the waves caused by the Alpha and Delta variants.

"Alpha and Delta were more like putting out serious forest fires. Difficult but doable. Putting out Omicron and its subvariants is like trying to basically stop the wind," Osterholm said.

"You can't. You can divert it but you can't stop it."

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