The Delta variant is the most dominant and deadly variant in the whole world. In its presence, all other strains, including the Alpha, Gamma, and Beta, seem to be losing their stronghold.
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To make matters worse, it seems as though the Delta variant isn’t done mutating quite yet. UK officials have been monitoring a sublineage of the strain, which some are calling the Delta variant plus.
AY.4.2
The UK Health Security Agency revealed information about the new mutation in a technical briefing that was published on 15 October. They are officially referring to this sublineage as AY.4.2, and pointed out that it has two mutations in the spike protein—A22V and Y145H. According to the last complete sequencing data, which was the week beginning on 27 September, the AY.4.2 mutation accounted for 6% of COVID cases. They said:
A Delta sublineage newly designated as AY.4.2 is noted to be expanding in England. It is now a signal in monitoring and assessment has commenced.
In the week beginning 27 September 2021 (the last week with complete sequencing data), this sublineage accounted for approximately 6% of all sequences generated, on an increasing trajectory.
Driving the current surge?
Not all mutations will have a significantly dramatic effect on the progression of the virus or its transmissibility, however experts are putting out a word of caution given that this specific mutation has been taking off in the UK. Dr. Jeffrey Barrett, director of the COVID-19 Genomics Initiative at the Wellcome Sanger Institute in Cambridge, and Professor Francoise Ballo, director of the University College London Genetics Institute told The Guardian:
Britain is the only country in which it has taken off in this way and I still would not rule out its growth being a chance demographic event.
They also believe that while the strain could possibly be more transmissible than the original Delta variant, it is not driving the current surge of new cases in the UK. They added:
It’s around 10% frequency [now], and assuming it may be 10% more transmissible, that would only explain an additional 1% extra infections [every five or so days].
