What is known so far about the XBB.1.5 variant of the coronavirus

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In recent weeks, there has been frequent talk that the pandemic has entered a final phase, and the massive waves of flu and RSV have also pushed the coronavirus into the background. But the rise in the number of cases in China, after the regime there abandoned its zero-covid policy, has brought Sars-CoV-2 increasingly back into the headlines. Millions of Chinese are now believed to be infected with the coronavirus. And the more infections there are, the more a virus can circulate freely, and the more likely new mutations are.

One virus variant that is currently the focus of attention is XBB.1.5. According to the World Health Organization (WHO), the virus is spreading primarily in the U.S. and Europe and has already been detected in 29 countries. For its part, the U.S. Centers for Disease Control (CDC) estimates that it was behind about 40.5 percent of all new infections in the United States in the week leading up to the new year. The variant could be more easily transmitted, according to the CDC. “We’ve been monitoring XBB.1.5 since mid-November, and its frequency has doubled about every week,” Richard Neher, head of the Evolution of Viruses and Bacteria research group at the University of Basel’s Biozentrum, told Deutsche Presse-Agentur.

In Austria, XBB.1.5 has been detected sporadically so far, according to molecular biologist Ulrich Elling of the Austrian Academy of Sciences.
XBB.1.5 – a member of the omicron family
XBB.1.5 also bears the epithet “Kraken”; it is still a variant from the now widely ramified Omicron family. In addition, XBB.1.5 is a recombinant of two Omicron BA.2 variants; it probably originated in New York.

The F486P mutation in the spike protein – the part of the virus that binds to human cells – is likely to give this recombinant an advantage. As a result, XBB.1.5 succeeds very effectively in escaping part of the human immune response, i.e. antibodies. On the other hand, the cellular immune response cannot evade even this variant, virologist Dorothee von Laer, as published by derStandard.

This may be part of why the variant discovered in October is more easily transmissible than any previously known variants, WHO Corona specialist Maria van Kerkhove – read an interview with her here – said Wednesday in Geneva.

It is unclear whether this variant also changes the disease burden of a Covid-19 infection – in other words, whether it also makes people more seriously ill. There are no indications of this from U.S. hospital data.