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Another omicron subvariant is gaining traction in the United States, the Centers for Disease Control and Prevention reported Tuesday. The subvariant, called BA.2.12.1, is an offshoot of the BA.2 version of omicron. While BA.2 remains the dominant variant in the U.S., BA.2.12.1 now accounts for roughly 1 in 5 new cases nationwide. The majority of cases in the U.S. — around 75 percent — are still caused by BA.2., which has been the country's dominant variant since late March. But BA.2.12.1, along with another version of omicron, called BA.2.12, is said to be responsible for the recent spike in Covid cases seen in upstate New York, the State Department of Health said last week. (Lovelace Jr., 4/19)

Scientists around the world are discovering and tracking newer forms of the Omicron coronavirus variant, showing how even when a strain becomes globally dominant, it continues to evolve and can splinter into different lineages. Case in point: Updated data released Tuesday showed that a burgeoning form of Omicron, called BA.2.12.1 —  itself a sublineage of the BA.2 branch of Omicron — now accounts for nearly one in five infections in the United States. It’s eating into the prevalence of the ancestral BA.2, highlighting the emergent virus’s transmission advantage over its parent. BA.2 now accounts for about 74% of cases, while the remaining 6% or so are from the BA.1 branch of Omicron, the first form of the variant that took over globally and whose prevalence has been falling as BA.2 became dominant. (Joseph, 4/19)

Arguably the most successful version of the Omicron coronavirus variant to date has been BA.2 – but it hasn’t been resting on its laurels. BA.2 has been picking up mutations, sometimes shifting into sleeker and, incredibly, even faster versions of itself. Global variant trackers have found 21 viral offspring associated with BA.2. Most of these look like underachievers, with mutations of little consequence. But two of these offshoots – BA.2.12.1 and BA.2.12 – have been fueling a rise in Covid-19 cases and hospitalizations in central New York state. And one of them, BA.2.12.1, is outpacing BA.2 in other regions, too. (Goodman, 4/19)

A new version of the Omicron coronavirus variant now accounts for 20 percent of COVID-19 cases in New England, the Centers for Disease Control and Prevention estimated Tuesday. But experts say it’s too soon to tell what the impact will be. The new subvariant, BA.2.12.1, was in the news after it was spotted along with another new subvariant in New York and blamed last week by officials there for pushing up cases in the central part of the state. The original Omicron variant BA.1 caused a terrifying surge that peaked early this year in the United States. Cases have plummeted since then, though they recently turned up again as the more contagious BA.2 subvariant has arrived. (Finucane, 4/19)

Most children from 5 to 11 years old hospitalized with COVID-19 during the U.S. surge driven by the Omicron variant were unvaccinated, per a Centers for Disease Control and Prevention study published Tuesday. The study of children hospitalized in the U.S. from Dec. 19 to Feb. 28 found the hospitalization rate was 2.1 times higher for those unvaccinated than their vaccinated peers. (Falconer, 4/19)