New Covid Variant LB.1

Recent weeks have seen an increase in test positivity rates and emergency room visits nationwide, raising concerns about a potential summer surge as the virus continues to evolve and spread.

LB.1 closely trails the dominant KP.3 and KP.2, according to the latest data from the U.S. Centers for Disease Control and Prevention (CDC).

As of July 6, KP.3 accounts for approximately 37% of cases in the U.S., followed by KP.2 at about 24%, with LB.1 driving 15% of cases.

Since late May, the share of cases attributed to LB.1 has doubled based on CDC data. Some experts suggest that this newly mutated variant could potentially surpass the FLiRT variants in the weeks ahead.

What information do we have regarding the new variants FLiRT and LB.1?

FLiRT consists of variants including, KP.2, JN.1.7, and others starting with KP or JN. These variants are derived from the JN.1 variant, which was predominant in infections in the U.S. from late 2023 to early 2024.

Its symptoms mirror those seen in earlier variants, featuring fever, cough, fatigue, and digestive problems, alongside an increased transmission rate. There is particular concern about its capability to evade immunity conferred by vaccines and prior infections.

The LB.1 variant, a mutation within the FLiRT cluster, accounted for 17.5% of Covid-19 cases in the US at the start of this summer. Both FLiRT and LB.1 demonstrate high transmissibility.

Initial research data from the Infectious Diseases Society of America indicates that the most prevalent FLiRT variants are mutations capable of infecting vaccinated individuals. These variants spread more readily than JN.1, with LB.1 showing potential for even greater infectivity and transmissibility compared to earlier strains.