New COVID Variant NB.1.8.1 'Nimbus' Now Driving 37% of Cases in US

As summer and peak travel season begins, a highly transmissible new COVID-19 variant called NB.1.8.1, or "Nimbus," is spreading in the United States. The mutated omicron subvariant, which caused surges in parts of Asia this spring, now accounts for more than one-third of cases in the U.S., new data show. ...

Although NB.1.8.1 is causing a rapidly increasing proportion of cases in the U.S., COVID trends — including test positivity and hospitalizations — remain stable. As of June 6, the level of COVID viral activity in wastewater is “low” nationally, according to the U.S. Centers for Disease Control and Prevention.

However, this is expected to change in the coming months, experts say. The U.S. has seen COVID-19 cases spike in the summer every year since 2020. The emergence of Nimbus has raised concerns about a possible surge.

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