Across a population that’s both undervaccinated and underexposed to the virus, up to 250 million people may have been infected in the first 20 days of December alone, according to a leaked estimate from Chinese health officials. In the eastern province of Zhejiang, home to more than 64 million people, the provincial government has reported around 1 million new cases a day. Infections are likely to escalate further this month following the Lunar New Year on January 22. The event is the world’s largest annual migration, as Chinese people travel across the country to gather with friends and family. “There’s going to be about a billion infections in China this winter,” predicts Ben Cowling, an epidemiology professor at the University of Hong Kong. “Starting within the next two weeks, any village in China which has so far managed to avoid Covid is not going to avoid it for much longer.” Domestically, this viral surge is nothing short of a crisis. Grim reports tell of hospitals being overwhelmed and huge queues to crematoriums, with modelers predicting that nearly 2 million Chinese people could die this winter because of the country not being ready to fully open up. At the start of November, 60 percent of over-80s in China were either not vaccinated at all or not boosted with a third dose. “They made this decision to rapidly transition out of the pandemic without a high enough vaccine coverage, without hospitals being prepared, without antivirals stockpiled, and so on,” says Cowling. But outside of China, this surge of new cases may be less of a concern than first appears. Epidemiologists point out that there’s already significant ongoing transmission of the coronavirus in most countries, and so incoming Chinese travelers are unlikely to trigger a noticeable spike in local Covid cases. “There are a lot of cases in China, but they represent just a fraction of cases in terms of the global picture,” says Francois Balloux, director of the University College London Genetics Institute. “It’s a major problem for China, but I’m not convinced it’s a major problem for the rest of the world.” Nevertheless, Australia, France, India, Israel, Italy, Morocco, Spain, the UK, and the US have all announced mandatory Covid tests for inbound Chinese travelers. Morocco has imposed a complete travel ban. However, the European Union has said these measures are “unjustified,” given the higher levels of immunity in places such as Europe, and that the variants infecting people in China are the same as those circulating in the West. Since Omicron was identified in November 2021, possessing a collection of completely new mutations that made it substantially more transmissible than any variant seen before, virologists haven’t detected anything radically different. From BA.5, which circulated widely in the UK during summer 2022, to XBB.1.5, which is currently spreading rapidly in the US, every notable variant that has appeared within the past 14 months has been a subvariant of Omicron. In 2020, Ravi Gupta, a professor of clinical microbiology at the University of Cambridge, published a paper in the journal Nature demonstrating that chronic SARS-CoV-2 infections—where the virus lingers and multiplies inside the body of someone whose immune system is compromised—provide the virus with a greater opportunity to evolve. “A billion new infections means more opportunity for more chronic infections,” says Gupta. “You’re upping the numbers game in favor of the virus to make new, potentially problematic variants.” But Cowling argues that because the level of immunity is much lower in China than the rest of the world, it will be relatively easy for the virus to spread through the population without needing to evolve. He says that if a new supervariant were to emerge, it might be more likely to come from North America or Europe, where more people have built up immunity through both vaccination and prior infection. “My gut instinct is that the risk of a major new variant is probably not higher in China,” Gupta says. “In the UK, for example, if Covid is going to continue circulating, it’s got to find a new direction and way around the immunity from previous waves of Omicron and all its subvariants, whereas in China it’s quite happily spreading anyway.” Even if a new supervariant does appear, scientists are unsure whether it would be more or less virulent than what’s already out there. Last year, Gupta and his colleagues showed that Omicron is less lethal than its predecessors because it does not infect lung cells as efficiently. “Instead it infects nasal cells,” he says. “Omicron chose a pathway that exists in the upper airways, so it’s less severe and transmits very, very well.” But Gupta cautions that this doesn’t necessarily mean that the whole trajectory of the virus has shifted to being less severe, and says it is still biologically plausible for an immune-evasive version to emerge that is more virulent. “There’s no evolutionary reason why the virus couldn’t go back to being quite pathogenic,” he says. Whatever happens, it’s possible that it will take some time before the full consequences of China’s Covid surge becomes apparent. While some global consortiums such as GISAID in Germany are still dedicated to tracking coronavirus mutations, in general, countries around the world have scaled down their efforts to sequence viral samples, making it harder to track new variants and how they are being introduced to different countries. “People have realized how much it costs, and it’s not just in the UK and the US—it’s happened globally,” says Gupta. “So for that reason, we are maybe at our most vulnerable at the moment, in a relative sense, just because we don’t know what’s out there.” For much of Europe and North America, Balloux describes Covid as currently being comparable to many other common respiratory infections, although that picture could change if a dangerous new supervariant were to emerge. The alarming spikes of cases, hospitalizations, and deaths of 2020 and 2021 have been replaced by a steady, more insidious death toll. Between January and November 2022, 41,620 people in England perished from Covid. Most are believed to have been elderly people who were already frail and suffering from multiple underlying health conditions, or people whose immune systems were suppressed—either because of illness or medicines they were taking—though no precise data exists. In comparison, a particularly severe flu season tends to result in around 30,000 fatalities. “There are very few young healthy people who die from Covid now in the UK or the US,” says Balloux. “What Covid does at the moment is essentially add to the stress of other issues—people who already have underlying problems, and the fact that in the UK, the hospital system can’t cope. It’s amplifying these underlying risks.” China’s Covid surge, at least for now, will do little to change this already-existing threat that the virus poses.
