Nice visual.
Based on early data BA.2 looks to potentially have a growth advantage over OG Omicron BA.1. It has been displacing BA.1 in Denmark.
The UK HSA has designated it a variant under investigation. It has ~20 unique mutations different than BA.1, but no sign of increased virulence or immune evasion at present. It is still early days on this sub-lineage. It could just mean this Omicron wave might last a bit longer than originally expected.
Notably it doesn't have S-gene deletion like BA.1, so S-gene target failure can't be used as a proxy for its detection. However since most cases in the US are BA.1, you could track the decline in overall S-gene target failure as a rough proxy for BA.2's prevalence.
It is already in the US, but in low numbers for now.
Ongoing genomic surveillance will be important even as the Omicron wave recedes. It isn't a given that the coronavirus will evolve to be less virulent with time or not have immune evasion. So it will be important to keep monitoring how this virus mutates.