New COVID-19 Variant KP.3.1.1 Dominates U.S. Cases, Poses Greater Challenge to Immunity
A new coronavirus variant named KP.3.1.1 has become the most prevalent strain in the U.S., nearly doubling in prevalence within two weeks, according to the Centers for Disease Control and Prevention. Experts warn that KP.3.1.1, which as of August 3 accounts for over 25% of U.S. COVID-19 cases, poses a greater challenge to our immune systems compared to previous variants.
KP.3.1.1 is a sub-lineage of the previously dominant KP.3, which emerged at the end of May. Together, KP.3.1.1 and KP.3 now represent nearly half of all U.S. COVID-19 cases, spreading amid a “summer wave” of infections.
Both variants are part of a new class called the “FLiRT” variants, named for the mutations in their spike proteins, which facilitate cell entry and are also targets for immune responses and vaccinations. Early, non-peer-reviewed analysis suggests KP.3.1.1 is significantly more infectious than earlier variants, including KP.3, and may better evade immune defenses and vaccine-induced immunity.
Eric Topol, a professor of molecular medicine at Scripps Research, stated on X (formerly Twitter) that KP.3.1.1 poses a greater challenge to immune response than KP.3 and previous variants, cautioning that the current wave of infections isn’t over due to KP.3.1.1’s emergence.
The rise of KP.3.1.1 follows a surge in COVID-19 detection in wastewater surveys across the U.S., with very high levels found in 20 states. Despite the CDC reporting a steady increase in infections, hospitalizations remain relatively low. The new FLiRT variants, though more infectious, generally do not cause severe symptoms. It is still important to isolate if symptoms develop.
CDC-listed symptoms include:
Fever or chills
Cough
Shortness of breath
Fatigue
Muscle or body aches
Headache
Loss of taste or smell
Sore throat
Runny nose
Nausea or vomiting
Diarrhea
Lawrence Young, a virus expert and professor of molecular oncology at the University of Warwick, emphasized the need to continue monitoring the spread of this variant.