What is Deltacron, the recombinant variant of the coronavirus?

• A new variant combining characteristics of the Delta and Omicron strains was discovered in France in January.

• It was born from simultaneous co-infections by the two strains, the genome of which merged to form Deltacron, a so-called recombinant variant.

• Is it therefore more dangerous?

  Should we be worried about its spread?

  20 Minutes

   takes stock of what we know about this new variant.

It was not very difficult to baptize.

Appeared in recent weeks in full overlap of the epidemic waves of Delta then Omicron, the Deltacron offspring is the synthesis of its two parents.

Two years after the official start of the pandemic, the World Health Organization (WHO) has just recognized the existence of this Deltacron variant.

Is it more dangerous?

Should we be worried about its spread? 

 takes stock of what we know about this variant from two strains of Covid-19.

What is Deltacron and where was it discovered?

As its name suggests, Deltacron is a hybrid variant, which combines in the same cell both characteristics of Delta, and others of Omicron.

By what mechanism?

“When an individual is co-infected with two different variants, a new strain, whose genome is a mosaic of the two initial variants, can emerge”, explains Public Health France, which carried out a risk analysis on the variants. emerging from SARS-CoV2.

More than a simple variant, Deltacron, which responds to the scientific name of AY.4/BA.1, is a so-called recombinant variant.

“We are aware of this recombination.

It's a combination of Delta AY.4 and Omicron BA.1,” WHO chief epidemiologist Maria Van Kerkhove confirmed on Wednesday, illustrating WHO's recognition of this Deltacron variant.

And it was in France that this recombinant was detected for the first time, on a sample taken on January 17, details Public Health France, which has set up reinforced monitoring of these Delta / Omicron co-infections “in order to detect possible recombinants as soon as possible”.

Should we be concerned about the appearance of this recombinant?

Is it more dangerous?

“We knew that recombinant events could occur, in humans or animals, with multiple variants of SARS-CoV2 in circulation.

We must wait for additional work to determine the properties of this virus, ”added Soumya Swaminathan, chief scientist of the WHO, on Twitter on Tuesday.

Before insisting on “the importance of sequencing, analysis and rapid sharing of data as we face this pandemic”.

Because even today, “it is difficult to predict what the characteristics of such a recombinant will be compared to the two parental variants and to anticipate its impact on public health.

This is why SARS-CoV-2 recombinants are the subject of careful monitoring on an international scale”, abounds Public Health France.

However, these recombinants, although "difficult to detect, are generally not of concern in terms of public health", reassures the health agency.

According to the researchers, the phenomenon is therefore neither rare nor inherently worrying.

“Before the emergence of Omicron, very few recombination events between two variants of SARS-CoV-2 were reported, because the genetic proximity between the circulating viruses made the detection of recombinants impossible, continues Public Health France.

But between December 2021 and January 2022, Delta and Omicron co-circulated in a large epidemic wave, which increased the likelihood of the emergence of recombinants.

Several detections of Delta/Omicron recombinants have been reported”.

In practice, "it happens whenever we're in a period of transition from one dominant variant to another, and it's usually a scientific curiosity, but nothing more than that,"

Dr Jeffrey told the

. Barrett, who previously led the Covid-19 genomics initiative at the Wellcome Trust Sanger Institute.

Moreover, confirms Public Health France, “this recombination phenomenon is frequent with SARS-CoV-2, an American study carried out on 1.6 million SARS-CoV-2 genomes having identified 2.7% of recombinants” .

Where was his presence confirmed?

For the time being, the distribution of this recombinant coronavirus is very limited.

According to the elements of the EMERGEN database (the Consortium for surveillance and research on infections with EMERgent pathogens via microbial GENomics coordinated by Public Health France and the ANRS-Emerging Infectious Diseases), "as of January 21, 10 sequences that could correspond to a Delta/Omicron recombinant have been identified in France”, reports Public Health France.

A month later, on February 21, 59 probable Delta/Omicron co-infections were identified in France.

In addition, 8 cases have been identified in Denmark, and one in the Netherlands as well as in Germany.

But as today, a wave of lifting of health restrictions is sweeping across Europe, “WHO is concerned that several countries are drastically reducing screening tests, lamented Friday the director of the WHO, Tedros Adhanom Ghebreyesus, on the second anniversary of the pandemic.

This inhibits our ability to see where the virus is, how it is spreading and how it is evolving.

Testing remains a vital tool in our fight against the pandemic, as part of a comprehensive strategy.”

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• Variant Omicron

• epidemic

• Covid-19

• Variant Delta

• Health

• Coronavirus

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