The highly contagious variant, LB.1, now accounts for 17.5 percent of US cases in the two weeks ending Saturday, June 22.
LB.1 cases have more than doubled since May, and some experts think it could be on a path to surpass two offshoots of the highly contagious Omicron variant who are part of the so-called "FLiRT" group: KP.3 and KP. 2.
Combined, those two subvariants account for more than half of COVID infections in the US.
In the latest data, the KP.3 strain made up 33 percent of cases nationally, an increase of 8 percent from the previous report.
The KP.2 strain, meanwhile, accounts for about 21 percent of cases.
LB.1 is an offshoot of JN.1, also an Omicron subvariant, which had dominated nationally before the "FLiRT" strains emerged.
None of the subvariants are expected to cause more serious symptoms than other COVID strains, according to experts.
According to CDC data for the period ending Thursday, June 27, virus levels in wastewater samples are increasing in most parts of the country.
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