BA.4.6, a subvariant of the omicron COVID variant which has been quickly gaining traction in the US, is now confirmed to be spreading in the UK.
The latest briefing document on COVID variants from the UK Health Security Agency (UKHSA) noted that during the week beginning August 14, BA.4.6 accounted for 3.3% of samples in the UK. It has since grown to make up around 9% of sequenced cases.
Similarly, according to the Centers for Disease Control and Prevention, BA.4.6 now accounts for more than 9% of recent cases across the US. The variant has also been identified in several other countries around the world.
So what do we know about BA.4.6, and should we be worried? Let’s take a look at the information we have so far.
BA.4.6 is a descendant of the BA.4 variant of omicron. BA.4 was first detected in January 2022 in South Africa and has since spread around the world alongside the BA.5 variant.
It is not entirely clear how BA.4.6 has emerged, but it’s possible it could be a recombinant variant. Recombination happens when two different variants of SARS-CoV-2 (the virus that causes COVID-19) infect the same person, at the same time.
While BA.4.6 will be similar to BA.4 in many ways, it carries a mutation to the spike protein, a protein on the surface of the virus which allows it to enter our cells. This mutation, R346T, has been seen in other variants and is associated with immune evasion, meaning it helps the virus to escape antibodies acquired from vaccination and prior infection.