Several countries have decided to impose restrictions on travelers from China, in particular by imposing screening tests. “This measure is essential to ensure the monitoring and individualization of possible virus variants with the aim of protecting the Italian population,” Italian Health Minister Orazio Schillaci said in a statement.
In fact, China is experiencing an unprecedented epidemic outbreak since Beijing ended its “covid zero” policy and this situation raises fears of the appearance of new variants that could give rise to new epidemic waves.
1.4 billion people suddenly exposed to the virus
According to the Global Virus Network, since the lifting of restrictions in early December, at least 250 million people have been infected with Covid-19 in China. Until recently, 660 million people around the world had contracted the virus since the start of the pandemic. The current circulation of the virus in China is extremely rapid.
A favorable situation for the appearance of variants. As Antoine Flahault, an epidemiologist and professor of public health at the University of Geneva, reminds us at BFMTV, since the start of the pandemic, every time the virus replicates virulently in a population, this gives rise to mutations and selection of variants. when these are more transmissible. Then they can assert themselves as the dominant variant.
“It happened in England, in Kent where the Alpha variant was, in India where Delta was or in South Africa with Omicron”, he explains.
In short, each new infection increases the chances that the virus will mutate. “The fact that 1.4 billion people are suddenly exposed to SARS-CoV-2 obviously creates favorable conditions for the emergence of variants,” adds Antoine Flahault.
low immunity in china
However, according to Marion Koopmans, a virologist at the Erasmus Medical Center in the Netherlands, the lack of herd immunity in China could prevent this. Indeed, the Chinese are very poorly vaccinated and have had little contact with the virus, due to the drastic restriction measures in the country since 2020.
However, one of the main triggers for viral evolution is the need for the virus to escape human immunity. It is this immunological pressure that causes a virus to evolve to evade antibodies. In China, there is almost no immunity.
“If the immunity is not very extensive, the selection pressure (on the virus) is not very strong,” explains Marion Koopmans to STAT. “So that could work against the selection of new variants.”
The virus evolves mainly to maintain its transmission capacity. In China, it is still very strong due to the low vaccination rate, especially among the oldest.
Westerners protected against Omicron subvariants
Despite this unique configuration, new sublineages of the Omicron variant have recently been detected in China. This is particularly the case for BF.7, a subline of BA.5 that became the majority in Beijing at the beginning of the month and is highly contagious.
“But we can imagine that the immune shield we currently have in France will still protect us, at least in severe forms,” Philippe Amouyel, an epidemiologist and professor of public health, explains on BFMTV.
In fact, today, bivalent vaccines, that is, updated to attack the initial strain of the virus but also Omicron, are used as a reinforcement of anti-Covid vaccination. “They are very effective on Omicron subvariants,” explains Benjamin Davido, an infectologist at the Raymond-Poincaré de Garches hospital.
Thus, the derivatives of Omicron that could emerge from China could be added to those that already exist and would not represent a strong danger for the well-immunized western population.
China’s information deficit
The risk remains if a variant develops that escapes this immunity and therefore has the potential to become dominant, causing new waves of contamination.
Also, it could happen over a longer period of time, once the Chinese population has developed some immunity. It is in particular in light of this possibility that several countries and experts are calling for 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 make it possible to circumvent any delay in information coming from Beijing and thus quickly identify if a new variant emerges.
On December 26, the 120 passengers on a Beijing-Milan flight underwent anti-Covid tests provided by the Lombardy region, the epicenter of infections in Europe at the beginning of 2020: more than half tested positive.
Source: BFM TV
