FAQ on COVID-19 subvariant XBB.1.5: What is it? Where is it prevalent? How does it differ from Omicron? Does it cause serious illness?

(The Conversation) Despite intensive public health efforts to grind the COVID-19 pandemic to a halt, the recent emergence of the highly transmissible, extensively drug-resistant and profoundly immune system-evading XBB.1.5 SARS-CoV-2 subvariant is putting the global community on edge. What is XBB.1.5? In the naming convention for SARS-CoV-2 lineages, the prefix “X” denotes a pedigree that arose through genetic recombination between two or more subvariants. The XBB lineage emerged following natural co-infection of a human host with two Omicron subvariants, namely BA.2.10.1 and BA.2.75. It was first identified by public health authorities in India during summer 2022. XBB.1.5 is a direct descendent, or more accurately, the “fifth grandchild” of the original XBB subvariant.