Covid variant or “scary”? Experts warn of a future “Deltacron” is possible

Health experts have questioned reports of a possible Covid-19 mutation combining elements from both the Delta and Omicron variants. While evidence of “Deltacron” is still scarce, French virologists warn that the emergence of such hybrid strains is a distinct possibility.

The talk of a possible new hybrid variant with a name from a Hollywood disaster B-movie spread like wildfire on social media this weekend, leaving behind the now usual trace of conspiracy theories and black humor. While some eminent scientists rushed to warn of the risk of trafficking in misinformation, others have argued that rampant variants make the threat posed by such mutant strains too real.

The controversy started on the Mediterranean island of Cyprus, which is currently plagued by Europe’s highest rate of infection for Covid-19, where a local team of researchers claimed last week that they had discovered the new variant. Led by Leondios Kostrikis, a professor of biological sciences at the University of Cyprus, the researchers said the new strain presented Omicron-like genetic signatures within the Delta genome – hence the name “Deltacron”.

Kostrikis told the local newspaper Cyprus Times that his team had found 25 cases of the mutation, including 11 cases among patients in hospitals with Covid-19. He noted a “higher frequency of mutations among hospital patients, which may indicate a correlation between Deltacron and hospital stays.” He added that it was too early to assess how contagious or dangerous the obvious new strain would be.

Variant or ‘scary’?

The results of the Cypriot team have been sent to GISAID, an international database that monitors and shares official data on Covid-19, giving other researchers access to the genetic details of “Deltacron”. Initial reactions have been skeptical at best, with prominent experts suggesting that the obvious new strain looks more like a “scariant” – an unconfirmed strain that causes a global fear – than a variant.

Although it is possible for coronavirus to genetically fuse, a process called biological recombination, experts noted that the alleged mutations identified by the Cypriot team were located on a part of the genome that is vulnerable to errors in certain sequencing procedures.

“The Cypriot” Deltacron “sequences reported by several major media outlets appear to be quite clearly contaminated, tweeted Tom Peacock, a virologist at the Department of Infectious Diseases at Imperial College London, over the weekend. In other words, according to Peacock, it was reported new strain most likely the result of a lab error, mixing samples from patients infected by Omicron and others by Delta.

Small update: the Cypriot “Deltacron” sequences reported by several major media outlets appear to be quite clearly contaminated – they do not cling to a phylogenetic tree and have an entire Artic primer sequencing amplicon of Omicron in an otherwise Delta backbone.

– Tom Peacock (@PeacockFlu) January 8, 2022

Kostrikis immediately struck back, telling Bloomberg News in an email that the cases he identified “indicate an evolutionary pressure on an ancestral tribe to acquire these mutations and not the result of a single recombination event.”

He pointed to at least one sequence from Israel deposited in a global database showing the genetic characteristics of the hybrid variant, adding: “These findings disprove the undocumented claims that deltacron is the result of a technical error.”

“Perfectly possible”

Since the beginning of the pandemic, researchers have struggled to counter a torrent of misinformation about Covid-19, much of it circulating online. Last week, unverified reports of a “flurona” or “fluron” virus – a combination of influenza and coronavirus – appeared, which the World Health Organization (WHO) dismissed on Monday.

In this context, it is hardly surprising that the news of a “Deltacron” was met with caution and skepticism among researchers. But according to Christian Bréchot, head of the Global Virus Network and a former head of the Pasteur Institute, there is “no reason to question the quality of the Cypriot team’s work.”

Of course, “from a technical point of view, it is important to ensure that no artifacts [editor’s note: lab contamination] proposes incorrect case of recombination, “Bréchot told FRANCE 24, adding that” additional data will be needed to confirm the new variant. “

“In principle, a recombination of different variants is entirely possible. This applies to viruses in general and coronavirus in particular, “he said. “When you have a high circulation level of two variants, the probability of them recombining increases significantly. And this would not be the first time this type of mutation occurs.”

Threats of future “Deltacrons”

Such a scenario is indeed quite possible, says virologist Christine Rouzioux, professor emeritus at the University of Paris-Descartes, while emphasizing the need for more information on the special case of “Deltacron”.

– It is still too early to draw conclusions [on ‘Deltacron’]”, she told FRANCE 24.” First we have to verify the sequencing and then analyze the results on a cluster of cases. But in theory, the combination is entirely possible. “

Whether this particular new strain is confirmed or not, the emergence of such hybrid variants remains an opportunity in the future, Bréchot warned: “As long as variants continue to flourish around the world, we will be left to this type of development. […] This situation is further proof of the fact that a strategy based on giving rich countries preferential access to vaccines is doomed to fail. “

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Delta seems to have originated in India and Omicron probably came from South Africa. Now we hear about Deltacron in Cyprus. It is clear that national strategies alone cannot work, “added Bréchot. “It is imperative that we define a global strategy, based on vaccinating people around the world.”

This article has been translated from the original into French.

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