In the United States, a new Covid-19 Omicron sub-variant that is seemingly even more infectious than the other Omicron variants so far is circulating, health experts warned.
A new sub-variant of Omicron – provisionally known as XBB.1.5 – is taking hold in the United States, where it already accounts for half of all recorded infections, according to the latest report from the US Centers for Disease Control and Prevention (CDC). In northeastern states such as New York, three-quarters of registered new cases are caused by the new subvariant.
XBB.1.5 appears to have resulted from the "recombination" of two existing Omicron subvariants. In that case, a new virus is produced by stitching together parts of the genome from two different sublineages, which can only happen in a patient simultaneously infected with two viruses, announced Dutch virologist Marion Koopmans on Twitter.
The new subvariant has then undergone some supplementary genetic changes, presumably making it better able to evade antibody defences (built up by vaccination or disease) against infection, she added.
This gives the new subvariant an infection advantage over existing Omicron subvariants, which are themselves highly infectious. It leads to XBB.1.5 appearing to be on its way to becoming the dominant variant in the US.
So far, no traces of XBB.1.5 have been found in Belgium but it has already crossed over to the European continent, virologist Piet Maes of the Rega Institute (KU Leuven) told De Standaard. "It has already been spotted in several other European countries, such as our neighbours France, Germany and the Netherlands."
For Maes, this indicates that Belgium should not focus too hard on Covid-19 variants that may enter from China, but that experts should continue to look globally at which variants may also pose a threat.
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The World Health Organisation (WHO) is not very worried about the US sub-variant. It is keeping an eye on it, but has currently only classified it as "of interest" and not "of concern," because there is no evidence that XBB.1.5 infection leads to more severe disease than those with the existing Omicron subvariants.
For now, it does not appear that more disease complications will occur for an XBB.1.5 infection, or that the protection offered by vaccination against severe disease and death will be compromised.
