The latest variant is XBB.1.5. Above is the spike mutations from the original. A recent paper indicates:
SARS-CoV-2 recombinant subvariant XBB.1.5 is growing rapidly in the United States, carrying an additional Ser486Pro substitution compared to XBB.1 and outcompeting BQ.1.1 and other XBB sublineages. The underlying mechanism for such high transmissibility remains unclear. Here we show that XBB.1.5 exhibits a substantially higher hACE2-binding affinity compared to BQ.1.1 and XBB/XBB.1. Convalescent plasma samples from BA.1, BA.5, and BF.7 breakthrough infection are significantly evaded by both XBB.1 and XBB.1.5, with XBB.1.5 displaying slightly weaker immune evasion capability than XBB.1. Evusheld and Bebtelovimab could not neutralize XBB.1/XBB.1.5, while Sotrovimab remains its weak reactivity and notably, SA55 is still highly effective. The fact that XBB.1 and XBB.1.5 showed comparable antibody evasion but distinct transmissibility suggests enhanced receptor-binding affinity would indeed lead to higher growth advantages. The strong hACE2 binding of XBB.1.5 could also enable its tolerance of further immune escape mutations, which should be closely monitored.
This is suspect ted to have originated in the US, New York City specifically. It is recent and may most likely have resulted from infections of immune compromised and/or um-vaccinated individuals allowing for multiple mutations. The above reference is from China and as usual the CDC seems clueless. This is a more aggressive form and may most likely see an explosion.
I had thought we had started to see the last of this but the gross failure of our Public Health system and lack of immigration control and foreign travel has opened this door again. This virus has a strong tendency to mutate, especially in patients whose immune system fails to respond, even those who may already be vaccinated.
Posts
