” is now causing more than a third of new omicron cases around the world, but scientists still don’t know how it could affect the future of the pandemic.
This week, a technical advisory group for the World Health Organization advised public health authorities to monitor it as a distinct omicron strain. 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.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. So while the test can detect a BA.
A bout with the original omicron also seems to provide “strong protection” against reinfection with BA.2, according to early studies cited by the WHO. But scientists are finding something different when they look at people. An initial analysis in Denmark showed no differences in hospitalizations for BA.2 compared with the original omicron, which tends to generally cause milder disease than the delta variant. More recently, researchers in South Africa found much the same: a similar risk of hospitalization and severe disease with the original omicron variant and BA.2.