Omicron variants KP.2, KP.3 and LB.1 have high prevalence in the United States. CDC projections estimate KP.3 to account for approximately 33% of new COVID-19 illnesses in the U.S. The proportion of illnesses caused by KP.3 rapidly increased from 9.4% estimated during the week of May 11 to 25% estimated during the week of June 11. As of June 25, the estimated percentage of illnesses caused by KP.2 is 20.8%, and the estimated percentage of illnesses caused by LB.1 is 17.5%.
Like KP.2 and KP.3, LB.1 is a descendent of the JN.1 variant. Unlike KP.2 and KP.3, however, LB.1 exhibits an additional mutation (S:S31del) in addition to the substitutions present in KP.2 and KP.3 that designate them as FLiRT variants. Variants with this deletion such as LB.1 may sometimes be referred to as âdeFLiRT,â indicating that the variant has the same mutations as other FLiRT variants with this additional deletion.
LB.1 is expected to overtake KP.3.