How bad is China’s Covid outbreak? It’s a science guessing game

Like Covid bin Through China, scientists around the world are searching for clues to an outbreak with huge consequences — for the health of hundreds of millions of Chinese, the global economy and the future. future of the pandemic.

But in the absence of reliable information from the Chinese government, it is a big game of scientific guesswork to determine the scale and severity of the increase in the world’s most populous country.

In Hong Kong, a team of researchers studied passenger data from five subway lines in Beijing to determine the likelihood of contagion. In Seattle, a group of modelers tried in vain to reverse engineer an unverified government leak. number of cases from Chinese health officials. In the UK, scientists are making their own estimates of the effectiveness of the Chinese vaccine.

Any personal anecdotes or social media report from China — scarce medicine, overrun hospital, overrun crematorium – could be fodder for the researchers’ models.

They are all trying to understand the same thing: How fast is the virus spreading in the country? How many people are dying? Could China be the source of a new and dangerous variant?

As scientists sift through various dubious sources of information, they are bracing for potentially dire outcomes. With the exception of new precautionary steps, some worst-case estimates suggest that Covid could kill as many people in China over the next four months as the number of Americans in the entire three years of the pandemic.

Without a satisfactory answer, some countries are placing limits on Chinese visitors, albeit partly based on unfounded fears or political motives. The United States, Italy and Japan said they would require a negative Covid test for people arriving from China, citing concerns that an increase in cases in China could create new variants. , more dangerous.

While researchers and virologists say the new measures will most likely do little, if any, to stop the spread, the policies reflect a limited vision of the outbreak. The scientists’ models often point to explosive spread and high mortality, given how many people in China have little or no immunity to sub-variants of Omicron. But even their estimates are everywhere.

Hong Kong researchers suggest that in some of the worst-case scenarios of what it means to end China’s “Covid-free” policy, nearly a million people could die in the early months of reopening. reported this month in a study partially funded by the Chinese Center for Disease Control and Prevention, although the study did not provide an exact time period.

An estimated group of Americans up to half a million people died in April and another million by the end of 2023 if China rejects social distancing regulations. Airfinity, a UK-based analytics company, this week provided a even more terrible than short-term forecast: 1.7 million Covid deaths as of the end of April.

Up until this month, the world seemed to have a pretty clear understanding of what was happening with the virus in China. The ruling Communist Party proudly announces its low daily number of infections and deaths as a testament to its strict “no Covid” policy. Nationwide system lock the doorquarantine and batch test largely suppressed the virus.

But in early December, the government abruptly abandoned “zero Covid”, leaving the scientific community largely in the dark.

“No one, no one has a clue,” said Siddharth Sridhar, a clinical virologist who focuses on emerging infectious diseases.

Predicting the path of a pandemic is always difficult. Even in places like the UK with reliable data, forecasts are often inaccurate. But scientists often use reported Covid deaths as a reliable barometer to determine the potential scale of an outbreak.

Data coming from the Chinese government cannot be trusted anymore. Officially, China has declared only 12 Covid deaths as of December 1. The country said it would count only those who died from respiratory failure directly related to the infection, ignoring the large numbers of people who died from aggravating Covid. add underlying disease or cause heart or liver failure.

Experts say the absolute rate of spread would indicate a much higher death toll. One city last week reported half a million cases in a single day. Another reported a million.

There are also signs that officials are pressuring doctors and crematoriums to avoid categorizing even the virus-related respiratory deaths.

A doctor at a private hospital in Beijing said he and his colleagues found a piece of typed paper on the hospital desk in recent days urging them to “try not to write respiratory disease caused by Covid” is the main cause of death. The note was shared with The New York Times.

The doctor said it was not clear whether the messages were generated internally or sent from government officials. But similar warnings have been circulated on Chinese social media asking doctors not to “carelessly write Covid” on death certificates.

Some modelers are even skeptical of leaks from government officials about case numbers, which are used to gauge the size of China’s outbreak. A recent estimate, making loops in news report and on Chinese social media, citing data from national health officials that 250 million people were infected in the first 20 days of December.

Some scientists say such huge numbers suggest that China has been hiding data for months or that they are trying to make it look like the outbreak has peaked.

Dr Christopher Murray, director of the Institute for Health Metrics and Evaluation at the University of Washington, said: “Either they know something we don’t, or they’re trying to say the worst is over. .”

“I suspect now is the second case,” he said, referring to the idea that China is trying to make it look like the worst is over. It seems that China cannot fake the numbers for months without raising suspicions, he said.

The shift in Chinese messaging is also complicating scientists’ assessments. Just a month ago, China’s state-controlled media warned of the dangers of the virus. The currentit is said that the current Omicron variant is mild and the outbreak is manageable.

However, scientists and public health experts worry that Omicron appears to be less severe elsewhere, largely because those populations have huge immune stocks, including infections. previously – a set of cases not found in China. If China manages to get through its outbreak without reintroducing public health measures or acceleration vaccination, scientists fear that many more people may die unnecessarily.

The Hong Kong researcherFor example, it has been found that the use of a fourth dose of vaccines and antiretroviral drugs as well as the use of social distancing measures could save at least 250,000 lives during China’s opening. back door. Dr. Murray’s team also found that social distancing duties can help hospitals avoid an increase in patient concentration, 200,000 deaths in April and even more so when combined with greater use of masks and antivirals.

How the Chinese public perceives the threat of the outbreak will also be important to its trajectory. Even if people decide to start taking more precautions for a short time, that could mean the difference between how hospitals can treat them, say the scientists. the sickest patients or completely overwhelmed.

Vaccination rates in the country are another large variable. While 90 percent of the population has received two injections, the rate of booster injections is Much lower for older Chinese. The World Health Organization says the three injections are crucial for a Chinese vaccine that uses an inactivated virus.

James Trauer, an expert in modeling infectious diseases at Monash University in Melbourne, Australia, said the potential for additional protection from additional doses would come in less than two weeks for those vaccinated. before. And he noted that the size of the country means the outbreak won’t hit everyone at once, giving some places more time to vaccinate more people.

Scientists are studying traffic patterns to understand the rate at which the disease spreads, but the picture is not clear.

Hong Kong scientists, in their recent study learn, analyzed passenger data from several subway lines in Beijing. They said information showed mobility in the city had dropped to a low as people stayed home to protect themselves against the virus.

But Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations, said there are some signs that at least in the big cities, traffic is increasing and restaurants are growing. getting busier and busier.

“That seems to challenge the notion that people are actually taking precautions,” he said.

With no clearer indication of how often fatal Covid-19 infections are in China, many scientists have relied on comparisons with Hong Kong. The Chinese territory, like China, is also slow to encourage vaccine use, particularly vulnerable when Omicron begins to spread there in early 2022.

Some models have assumed that China would have a very similar infection mortality rate to Hong Kong in the early stages of the outbreak. Before that, nearly 10,000 people in the territory of 7.5 million people died within months of Omicron spreading. The equivalent figure in China, with 1.4 billion people, would be much higher.

But there are also important differences. China had higher vaccine coverage for its older population than Hong Kong at the start of the spike.

However, based on the timing of their respective outbreaks, China’s mass vaccination campaign took place earlier than in Hong Kong, meaning the effects of vaccination took longer. Hong Kong also offers a Western vaccine option with newer mRNA technology, while China relies entirely on domestically produced, less effective vaccines. Hospitals may also have a harder time handling the surge in some parts of China.

The general lack of clarity has led to concerns that the size of the outbreak could create more opportunities for the virus circulating throughout China – an imported version of Omicron – to mutate into a dangerous variant. than.

But scientists are skeptical of such a scenario in China’s current outbreak.

Variants similar to those reported by China have been largely outnumbered months ago in the United States by Omicron sub-variants that are more contagious or more elusive. After Italy mandated testing for travelers from China, it said the first cases sequenced were all caused by an Omicron variant already present in Italy. European Union health officials said on Thursday that screening travelers from China was unjustified.

James Wood, an infectious disease expert at the University of New South Wales in Sydney, said: “We’ve had a large number of cases globally, estimating that most people globally have already been infected. virus infection. “That’s more cases than happened in China alone.”

Additional reporting and research by Zixu Wang, Joy Dong and Elisabetta Povoledo.