The "FLiRT" coronavirus variants account for more than two-thirds of all U.S. cases, according to the CDC's latest variant proportion estimates.
The FLiRT variants refer to a group of variants — including all that start with the letters "KP" or "JN" — that have independently acquired the same set of mutations in their spike proteins, according to the Johns Hopkins Bloomberg School of Public Health in Baltimore.
In total, these strains account for 65.2% of COVID-19 cases in the week ending June 8, CDC data shows. KP.3 is the nation's dominant strain, accounting for 25% of cases, while KP.2 makes up 22.5% of cases.
The FLiRT variants are descendants of the JN.1 strain, which emerged last September and became dominant by late December. At present, JN.1 accounted for just 3.1% of cases in the week ending June 8.
Two more COVID-19 updates:
1. Health experts said it's possible the FLiRT variants could fuel an uptick in COVID-19 infections this summer. While virus activity remains low nationwide, the CDC's wastewater surveillance data suggests it may be rising slightly. In the week ending June 1, the national wastewater viral activity level was 1.60, up from 1.23 in the week ending May 4. This figure has been decreasing since peaking at 12.7 in December 2023.
2. On June 5, the FDA's Vaccines and Related Biological Products Advisory Committee unanimously voted to update the COVID-19 composition this fall to target the JN.1 variant. The committee also discussed whether the new vaccines should target a more specific sublineage of JN.1, such as KP.2. The FDA is expected to formally recommend a final vaccine composition for drugmakers in the coming weeks.