#17,420
As we've seen before with the CDC's Nowcast of COVID variants, when a new variant appears we often see frequent revisions to weekly estimates during the first few weeks. As stated last week (and in nearly every blog on Nowcast):
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.
Projections for an emerging lineage with a high growth rate may have a higher degree of uncertainty (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.
Last week, XBB.1.16 debuted at 7.2% nationwide, with a surprising 21.3% share in Region 6 (TX, NM, LA, OK). This week, Region 6 has been rolled back to 14.4%, and nationally XBB.1.16 is now estimated at 9.6%.
Since last week's national estimate was also revised downward (to 5.7%) this represents about a 67% increase over last week's (revised) numbers.
Although believed to be more transmissible, we've not seen any evidence that XBB.1.16 produces any greater severity of illness than earlier Omicron variants, but that is based on limited data.
XBB.1.5 remains hugely dominant at over 73% of cases, and it will take a few more weeks before we'll have an idea of how much of an impact XBB.1.16 will have in the United States.
