Covid-19: the existence of “Deltacron”, a merger of Delta and Omicron, “is very likely”

Published on : 01/10/2022 – 5:49 PM

Are we all witnessing the birth of Deltacron, marriage of the Delta and Omicron variants for better or for worse? If the name of this new variant may have amused or annoyed Internet users on social networks this weekend, fueling new schoolboy jokes and conspiracy theories, the track of the fusion of these two variants of Covid-19 is taken very seriously. by the scientific community.

Everything this time seems to have started from Cyprus. On this island bathed by the Mediterranean where the incidence rate is the highest in Europe since the start of the year, Leondios Kostrikis, professor of biological sciences at the University of Cyprus and head of the Laboratory of Biotechnology and Molecular Virology, announced that he had discovered a fusion of the two variants. “There are currently Omicron and Delta co-infections, and we have found this strain which is a combination of the two,” the scientist told the private Cypriot channel Sigma TV at the end of last week. “The genetic signature of Omicron and the genomes of Delta”, hence the Deltacron contraction, specifies the academic. According to the Cyprus Times, 25 cases have been identified, 11 of which come from people hospitalized following contamination with Covid-19. In the newspaper’s columns, the doctor argues that “the frequency of mutations was higher among those who are in the hospital, which may lead to believe that there is a correlation between Deltacron and hospitalizations”. And to conclude, “we will see in the future if this strain is more pathological or more contagious or if it will prevail.”

First, prudence and skepticism of scientists

After having sequenced the viruses detected in the positive tests in question, that is to say fully dissected their genome, samples were sent on January 7, to the international structure GISAID, which ensures the sharing of official data on the Covid -19. At first, the announcement of the discovery aroused great suspicion among scientists. On social networks, some of them quickly explained that it must be a sequencing error, very common in the matter, like Tom Peacock, virologist at the prestigious Imperial College. “The Cypriot ‘Deltacron’ sequences which several mainstream media are talking about seem to be quite clearly a contamination, they do not group together on a phylogenetic tree”, assured the British scientist on Saturday on his Twitter account. In other words, “Deltacron” would only be a confusion of samples between patients contaminated by Omicron, and others by Delta, suggesting a fusion between the two variants.

Except that Leondios Kostrikis confirmed his results. On January 9, the Cypriot professor even personally replied to Tom Peacock “refuting the unsubstantiated claims that Deltacron is the result of a technical error”, echoed the Bloomberg agency. The cases of “Deltacron [identifiés] indicate an evolutionary pressure on an ancestral strain to acquire these mutations and not the result of a single recombination event, “the scientist justified himself. Moreover,” Deltacron “would also have been found in Israel, assures the Cypriot virologist .

A very likely scenario

“This announcement was received, at first with a lot of skepticism if not cautious”, assures Professor Christian Bréchot, virologist, president of the Global Virus Network and former director of Inserm and the Institut Pasteur, in an interview with France 24. But the Cypriot team has confirmed its results and there is no reason to doubt the quality of their work. ”

Certainly, “on the technical level, it is necessary to take care that there are no artefacts which could lead wrongly to believe in a recombination, continues the French professor living in the United States. It will probably be necessary to other data to confirm this new variant. ”

From a scientific point of view, this kind of event is quite probable. “In principle, the recombination of different variants is perfectly possible, continues Professor Bréchot. This is true for viruses in general, and it is even more true for Coronaviruses. As long as there is circulation high of two variants, the probability that there will be a recombination of the two is greatly increased. And this would not be the first time that this type of mutation has occurred. ”

A necessary global strategy

An observation shared by Christine Rouzioux, professor of virology emeritus at Paris-Descartes University, interviewed by France 24. If she has not yet had time to look with precision on the sequencing in question, this scenario can very clearly be considered. “It is still too early to say anything about it. We must first of all check the sequencing and analyze the results on a cluster, but this combination remains very possible.”

There is also the question of the real risk of the Deltacron. If it is confirmed by the whole of the scientific community, “it is still too early to say anything about its contagiousness and its severity. Nobody knows anything about it for the moment”, recognizes Professor Bréchot.

One thing is certain, concludes the French virologist: “As long as the variants continue to spread around the world at a high level, we will remain at the mercy of this kind of event. Deltacron may not have any negative impact. , this is what we must hope. While waiting to determine it, this situation illustrates above all to what extent a strategy based on the priority vaccination of the rich countries cannot solve the problem. “India, Omicron probably from South Africa. Today there is talk of a Deltacron in Cyprus. In this context, it is clear that purely national strategies alone are not enough. It is imperative to define a global strategy , based on vaccination around the globe. ”