WORLDWIDE SPREAD BA.2 has been found in more than 80 countries and all 50 U.S. states. In a recent report, the WHO said BA.2 was dominant in 18 countries and it represented about 36% of sequenced omicron cases submitted in the most recent week to a publicly available international database where scientists share coronavirus data.
That's up from 19% two weeks earlier. In the United States, BA.2 caused about 4% of COVID cases during the week ending Feb. 19, according to the Centers for Disease Control and Prevention.
The percentage was lower in some regions and higher in others – hitting about 7% in New England. WHAT’S KNOWN BA.2 has lots of mutations.
It's been dubbed “stealth" because it lacks a genetic quirk of the original omicron that allowed health officials to rapidly differentiate it from delta using a certain PCR test.