New data Tuesday from the Centers for Disease Control and Prevention show omicron’s more transmissible BA.2 subvariant now accounts for more than a third of the virus circulating in the U.S. but is not yet driving a surge in cases here as it has overseas.
The CDC data show that as of March 19, BA.2 — often referred to as “stealth omicron” — accounted for 34.9% of genetically sequenced samples across the U.S., up from 22.3% as of March 12 and 12.6% on March 5. In the Northeast, BA.2 accounts for as much as 55.4% of the virus, and in Western states including California, 41.3%.
Dr. George Rutherford, a professor of epidemiology and biostatistics at the University of California-San Francisco, said the increase is “about what I expected” given the subvariant’s transmissibility.
