The CDC Nowcast is now breaking out BA.1.1 from B.1.1.529 (BA.1). BA.1.1 is a sub-lineage of BA.1 (the original strain). BA.2 is not a sub-lineage of BA.1, but a sister strain.
BA.1.1 became the dominant Omicron strain about a month ago in the US. It is now 73.2% of cases in the US.
BA.2 though should eventually overtake it over the next 1-2 months. It is now only 3.9% of cases.
Both appear to be more transmissible than the original Omicron strain, but no indication of reduced vaccine effectiveness or increased severity. They should just prolong this wave.
Delta is effectively not present in the US anymore.