No sooner than you thought all the talk of new COVID-19 variants was over, there’s news of yet another one: AY.4.2. But what is it, where did it come from, and should we be concerned?

AY.4.2 is what’s termed a “lineage”. These are labels given to branches of the COVID-19 evolutionary tree to illustrate their relatedness.

They are overseen by the diligent Pango network, a joint team of researchers from the universities of Edinburgh and Oxford, who act as the custodians of lineages and handle the assignment of new ones.

If we go back to April of this year, we can trace the origins of AY.4.2.