Several countries and experts fear that China is becoming a breeding ground for the emergence of new variants, while Beijing has stopped communicating figures or information on the country’s disease situation.
Several countries have decided to introduce restrictions on travelers from China, notably by imposing screening tests on them. “This measure is essential to ensure the surveillance and individualization of possible variants of the virus with the aim of protecting the Italian population,” Italian Health Minister Orazio Schillaci said in a statement.
Indeed, China is experiencing an unprecedented epidemic outbreak since Beijing ended its “zero Covid” policy, and this situation raises fears about the emergence of new variants that could lead to new epidemic waves.
1.4 billion people are suddenly exposed to the virus
At least 250 million people in China have contracted Covid-19 since restrictions were lifted in early December, according to the Global Virus Network. Until recently, 660 million people worldwide had contracted the virus since the pandemic began. The current spread of the virus in China is extremely fast.
A favorable situation for the emergence of variants. As Antoine Flahault, epidemiologist and professor of public health at the University of Geneva, reminds us to BFMTV that since the beginning of the pandemic, every time the virus replicates virulently in a population, this leads to mutations and selection variants when these are more transferable. You can then assert yourself as the dominant variant.
“It happened in England, in Kent, where there was the Alpha variant, in India, where there was Delta, or in South Africa with Omicron,” he explains.
In short, each new infection increases the likelihood that the virus will mutate. “The fact that 1.4 billion people are suddenly exposed to SARS-CoV-2 obviously creates conditions that favor the emergence of variants,” adds Antoine Flahault.
Low immunity in China
However, the lack of herd immunity in China could prevent this, according to Marion Koopmans, a virologist at Erasmus Medical Center in the Netherlands. In fact, due to the drastic confinement measures in the country since 2020, the Chinese have been very poorly vaccinated and have had little contact with the virus.
However, one of the main triggers of viral evolution is the need for the virus to escape human immunity. It is this immune pressure that causes a virus to evolve to evade antibodies. There is almost no immunity in China.
“If the immunity is not very extensive, the selection pressure (on the virus) is not very strong,” Marion Koopmans tells STAT. “So that could counteract the selection of new variants.”
The virus evolves primarily to maintain its transmission capacity. In China, it is still very strong because of the low vaccination rate, especially among the elderly.
Westerners protected from Omicron subvariants
Despite this unique configuration, new sublineages of the Omicron variant have recently been discovered in China. This is particularly true for BF.7, a subline of BA.5 that became a majority in Beijing earlier this month and carries a strong risk of contagion.
“But we can well imagine that the immune shield that we currently have in France will still protect us, at least from severe forms,” explains Philippe Amouyel, epidemiologist and professor of public health, on BFMTV.
In fact, today bivalent vaccines, ie updated to target the original strain of the virus but also Omicron, are used for booster vaccinations against Covid. “They are very effective on the subvariants of omicron,” explains Benjamin Davido, an infectious disease specialist at the Raymond Poincaré Hospital in Garches.
Thus, Omicron derivatives emerging from China could be added to those already in existence and would not pose much of a threat to the well-immunized Western population.
China’s information deficit
The risk remains if a variant that evades this immunity evolves and thus has the potential to become dominant and thus trigger new waves of contamination.
It could also happen over a longer period of time once the Chinese population has developed some immunity. In view of this possibility, several countries and experts are demanding screening tests for all passengers from China.
“The main interest is to overcome the lack of information that we have at the level of China, which no longer communicates its figures,” explains Philippe Amouyel.
Testing and sequencing would thus make it possible to bypass delays in the information from Beijing and thus quickly identify whether a new variant emerges.
On December 26, the 120 passengers on a flight from Beijing to Milan were subjected to anti-Covid tests provided by the Lombardy region, the epicenter of contagion in Europe in early 2020: more than half were found positive.