Variant NB.1.8.1 accounted for 0% of U.S. cases in April. By mid-June, it was estimated to be the cause of around 37% of cases.

Less than 20 cases of the new COVID-19 variant, NB.1.8.1, had been reported in the U.S., as of Tuesday, May 27.

Summer wave New COVID variant swiftly gains ground in US; concern looms for summer wave The variant, NB.1.8.1, has been linked to surges in parts of Asia.