An explosion in China of Covid-19 cases, as the country lifts its “zero Covid” measures, could create potential breeding ground for the emergence of new variants, warn health experts.

China has just announced the end of mandatory quarantines on arrival in the country on January 8, the last remnant of the policy of strict restrictions that have kept the country largely closed to the world since the start of the pandemic.

While the government has stopped publishing daily case counts, officials in several cities estimate that hundreds of thousands of people have recently been infected, while hospitals and crematoria are overwhelmed across the country.

With the virus now free to circulate in China, which has almost a fifth of the world’s population, several countries and experts fear that China could become fertile ground for the emergence of new variants. Especially since the Chinese population remains poorly vaccinated.

Each new infection increases the chances that the virus will mutate, estimates Antoine Flahault, director of the Institute of Global Health at the University of Geneva. “The fact that 1.4 billion people are suddenly exposed to SARS-CoV-2 obviously creates conditions conducive to the emergence of variants,” he told AFP.

Bruno Lina, professor of virology at the University of Lyon, France, meanwhile told La Croix newspaper: “Given the intense circulation of the virus, and therefore the increased risk of mutations, a potential breeding ground for viruses could emerge of China”.

Soumya Swaminathan, who served as the World Health Organization’s (WHO) chief scientist until November, also said much of the Chinese population was vulnerable, in part because many elderly people have not been vaccinated. “We need to closely monitor any emergence of worrying variants,” she told the Indian Express newspaper website.

Border controls

In response to the surge in cases, the United States, Italy, Japan, India and Malaysia announced this week that they would tighten their border controls.

Washington will require a negative Covid test from January 5 for all travelers coming by plane from China.

The French government, which ensures “to follow very carefully the evolution of the situation”, said it was “ready” Wednesday “to study all the useful measures”.

India and Japan will impose mandatory PCR tests on all passengers arriving from China, a measure that Antoine Flahault says could be a way to circumvent any delays in information from Beijing.

“If we succeed in sampling and sequencing all viruses identified in all travelers from China, we will know almost immediately if new variants are emerging and spreading” in the country, he said.

Xu Wenbo, the head of the virus control institute at the Chinese Center for Disease Control and Prevention, said hospitals across the country will collect samples from patients and upload the sequencing information to a new national database. , which will allow authorities to monitor new strains in real time.

“Soup” of variants

More than 130 new sublineages of the Omicron variant have been detected in China over the past three months, he said last week.

Among them are XXB and BQ.1 and their own sub-lineages, which have spread across the United States and parts of Europe in recent months as a swarm of sub-variants vie for dominance in the world. entire.

However, BA.5.2 and BF.7 remain the main Omicron strains detected in China, Xu Wenbo said, adding that the different sublineages are likely to co-circulate.

“A soup” of more than 500 new sub-variants of Omicron has been identified in recent months, recalled Antoine Flahault.

“All variants, when more transmissible than previously dominant variants – such as BQ.1, B2.75.2, XBB, CH.1 or BF.7 – definitely represent threats, as they can cause new waves” , said the epidemiologist.

“Today, none of these variants appear to pose particular new risks of more severe symptoms, but new variants may in the near future,” he added.