Last week the CDC update showed variant “Ba.1.1.526” increasing quickly to 6.6% of all cases. Although they did not note it, I wrote that this was almost certainly Ba.4/5; they simply had not made the change yet.
Well, this week they did. This morning’s “nowcast” update of variants shows Ba.1.1.526 having vanished, with Ba.4/5 having taken its place, and having doubled to 13% of all cases in the past week, even as Ba.2.12.1 slowly increased from 59% to 62%:
Here’s the regional breakout:
Ba.2.12.1 now makes up a little over 80% of cases in NY, NJ, and PR, while BA.4/5 combined make up 18% of all cases in the northern Rockies and 22% of the southern Plains, including Texas.
It is unclear at this point how much if at all, nationwide cases will increase. It depends on how much Ba.2.12.1 fades compared with how quickly Ba.4/5 takes over. In South Africa, the Ba.4/5 wave rolled in and out very quickly earlier this spring:
There, the Ba.4/5 wave rolled in over about a 3-week period and rolled out almost as quickly. Cases were only 1/3rd as many as the original Omicron wave at peak, while deaths were only 1/5th as high. Hopefully the same will happen here.