#16,660
Last week, for the very first time, the CDC estimated that in two HHS regions of the United States (I & II: Connecticut, Maine, Massachusetts, New Hampshire, New York, New Jersey, Rhode Island, and Vermont, Puerto Rico and the Virgin Islands.) the BA.2 variant was the dominant strain, while the nation as a whole reported 34.9% of cases belonging to BA.2.
As a result, late last week the FDA announced that the monoclonal antibody sotrovimab - which is not believed to be effective against BA.2 - could no longer be used in those regions.
Fast forward 7 days, and now the CDC's Nowcast estimates nearly 55% of the nation's cases are BA.2, with only parts of the Midwest and deep South still showing BA.1.1 as their dominant strain. Given the gains in those regions by this emerging variant, it is likely BA.2 will become dominant in all states by next week.
Given the limits of surveillance, testing, and genomic sequencing around the country, all of these numbers should be viewed as rough estimates.
A similar trajectory has been reported around the world with BA.2 replacing BA.1 and B.1.1.529 at a remarkable rate. In some countries, this has led to a resurgence in cases, although we've yet to see that effect here in the United States.
While data on BA.2 remains limited - and is further complicated by the recent emergence of sub-variants (BA.2.2, BA.2.3, etc.) around the globe - in European countries where it has become dominant, we haven't seen any compelling evidence suggesting it is any more severe than BA.1.1.
But BA.2 does transmit more efficiently than earlier Omicron variants, which can mean a lot of people can be infected in a short period of time, and that can still put pressure on health care providers.
For now, the United States is enjoying a lull in cases. How long that can last is anyone's guess.
