XBB.1.5 is now estimated to make up about 75% of all cases in the United States, while CH.1.1 has slipped back to 1.3%. Previously dominant BQ.1.x strains continue to lose ground as well.
All of these numbers are estimates,revisions to previous week's numbers are common, and are more useful for spotting trends than nailing down exact percentages. The CDC has recently added the following caveat to their report.
(wider predictive interval) when it is just beginning to spread and still has low weighted estimates. Projections may also be biased during times of delayed reporting (e.g., around holidays). CDC performs frequent evaluations of Nowcast to inform performance improvements.