In less than a month, its share among new Covid cases has gone from less than 5% to almost half in the United States. The XBB.1.5 variant, one of the many members of the large Omicron family, has established itself at breakneck speed across the Atlantic. It supplanted BQ.1, which has a large majority in Europe and particularly in France. Will he win there as well?
This variant, derived from the “recombinant” XBB, has a growth advantage close to 140% compared to previously circulating lines, whether in North America or Europe, reports the European Center for Disease Prevention and Control ( ECDC) in a report released Thursday evening. This means it spreads much, much faster than previous variants.
This growth advantage is probably explained by its ability to resist immunity more than the previous variants, whether due to vaccination or infections. But also by the presence in its genome of the S486P mutation, which could provide it “either a transmissibility advantage, or additional immune evasion, or both”, indicates the ECDC.
Contexts not necessarily comparable
XBB.1.5 is already present in France. Between 30 and 40 cases have already been identified by sequencing, the technique of analyzing the entire genome of the virus. This number being quite low, “it is difficult to estimate whether there is a tendency to increase or not”, indicates Justine Schaeffer, in charge of monitoring variants at Public Health France.
According to the ECDC, XBB.1.5 “will not necessarily become dominant in Europe, since major differences in variant circulation have been observed with North America on several occasions during the pandemic”. “Vaccination coverage, but also the circulation history of variants and the temporality of successive waves differ greatly between the United States and France. For these reasons, even if XBB.1.5 ticks all the boxes to establish itself in France, its progress could be slowed down”, abounds Yannick Simonin, lecturer in virology at the University of Montpellier.
“The one with the most likelihood of winning in Europe”
France could also “benefit” from emerging from a 9th wave carried by the BQ.1 variant (essentially its “little brother” B.1.1), undoubtedly larger than that in the United States. The problem: there is not yet solid data concerning the protection conferred by a BQ.1.1 infection against XBB.1.5. Moreover, “the success of the introduction of a variant may very much depend on possible superpreader events (or superspreaders) “says Justine Schaeffer.
The fact remains that “among the myriad of variants identified so far, XBB 1.5 is currently the one with the greatest likelihood of winning in Europe,” says Yannick Simonin. However, as there is currently little presence there, the new epidemic wave that it could cause will not take place “in the coming month”, indicates the ECDC. Whatever happens, the good news is that XBB.1.5 doesn’t seem any harsher than the previous ones.