Lonelyplanet
“ Variant to watch is the AY.3 version of delta. It is most prevalent in the US but is increasing (still in very small numbers) here.”
All these sublineages of delta are just delta but with some markers of different origins. So AY.3 is not a variant at all.
Within a variant e.g. delta there are mutations which have no impact whatsoever on the virus protein structure, but they are useful for epidemiologists to follow where things are coming from and going to (e.g. I would expect someone at PHE is right now having a bloody good look at Broadmasters). These are the sublineages.
However, it is important to point out these sublineages are reflecting transmission already ongoing not reflecting any particular benefit of that sublineage or any transmission driven by that sublineage.
A number of well known and well respected academics came out yesterday to add this context to what Christina Pagel was saying, because she was leaving the impression there was cause for concern.
QueenStrombalinked to Andrew Rambaut’s thread on it on Twitter, which is excellent.
Like MRex, I am awaiting the PHE technical report today with interest. Not because of any delta AY.X sublineages (although that will be interesting), but because I want to see their update on B.1.621 originally from Columbia and present in Spain. This is “Beta-like” and I expect it to be promoted to VoC, although crossing fingers it is not able to outcompete delta.