While the variant BA.2 d’Omicron is currently the majority in France, the virus is constantly mutating. The Deltacron variant, also called the XD variant, is also in circulation in France. Earlier this week, health authorities in the United Kingdom this time issued the alert about a new variant that they fear is even more contagious: the XE variant. According to the British government website, 637 cases of this new variant have been detected in the country since January 19. We are not talking this time about Deltacron, a hybrid variant of Delta and Omicron, but about the XE variant, a recombinant of two strains of Omicron: BA.1 and BA.2. This variant could spread 10% faster than the current strain, but scientists said they are still studying it.
Variant XE: an even more contagious mutation?
“The recombinant variants are not an unusual phenomenon, especially when there are multiple variants in circulation, and several have been identified during the pandemic to date. As with other types of variants, most will disappear relatively quickly,” reassures Professor Susan Hopkins of the UK Health Security Agency (UKHSA).
According to her, this particular recombinant, XE, “has shown a variable growth rate and we cannot yet confirm whether it truly has a higher rate of contagion”. “So far, there is not enough evidence to draw conclusions about the transmissibility, the severity or the effectiveness of the vaccine”, procrastinates Susan Hopkins. A UKHSA report indicates that “XE shows evidence of community transmission in Englandalthough it currently accounts for less than one percent of total sequenced cases.”
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“Recombinants that contain the spike and structural proteins of a single virus (like XE or XF) are quite likely to act in the same way as their parent virus…“, assures Tom Peacock, virologist at Imperial College London. “XD is perhaps a little more concerning… It has been found in Germany, the Netherlands and Denmark and it contains the structural proteins of Delta. If any of these recombinants were to act very differently from its parent, it could be XD…”, assures the scientist.
According to data from Public Health France dating from March 17, there were 41 sequences of the XD hybrid variant detected in France. “These sequences correspond to cases from several regions and dating back to early January 2022, which suggests circulation at low levels for several weeks”, specifies the national public health agency.
In its epidemiological update of March 23, Public Health France explains that this new variant is composed :
- mostly from the genome of the Delta variant “which corresponds to the AY.4 sub-lineage”;
- a small portion of the variant genome Omicron (BA.1 subline): the S gene which encodes the Spike protein (the one which allows the virus to bind to the ACE2 receptor of human cells before penetrating inside to infect them).
“All of these recombinant variants, including the smaller clusters, should be monitored closely for signs of growth and attempts should be made to isolate and characterize them if possible,” concludes scientist Tom Peacock.