COVID-19 variant AY.4.2 is found to be more transmissible than Delta; new name may be Nu

AY.4.2 raised concern upon its discovery in the U.K. after it started making up a large number of new cases. Originally it was only 4% of new cases, but as recently as Oct. 9 it made up for 10% of new cases over a two week span.

In September it made yo for just 4% of new cases.

Data shows it may be 15% more transmissible than Delta.


Professor Francois Balloux, director of the University College London Genetics Institute, believes this may be the most infectious variant since the pandemic started. He believes the WHO will now change AY.4.2 to a variant under investigation and give it a Greek letter.

As of now the U.K. is the only country seeing it spread this way.

It’s unknown what this variant may do, and isn’t like Delta replacing the original virus. Delta was up to 50% more transmissible when it became the main variant, and AY.4.2 is only 15% more transmissible.

It is also not known if the surge in cases in the U.K. are because of AY.4.2 or not.

Two mutations are being watched in relation to AY.4.2 as well: Y145H and A222V.

Related: Delta Plus, or AY.4.2, is now in Massachusetts


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