known as BA.2, while warily watching it become ever more prevalent.
Early research suggests it spreads faster than the original omicron and in rare cases can sicken people even if they’ve already had an omicron infection. There’s mixed research on whether it causes more severe disease, but vaccines appear just as effective against it. 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.out of Denmark. Study authors noted 187 total reinfections, including 47 with BA.2 occurring shortly after a bout the original strain, mostly in young, unvaccinated people with mild disease. They concluded that such reinfections do occur but are rare. Like other early studies on BA.
“We always have to interpret studies in animals with caution,” Long said. “I place more weight in studies of actual patients and what they’re experiencing.”COVID-19 cases are dropping globally, including in some of the places where BA.2 is prevalent.