Experts are closely watching KP.2, now the leading variant.

For most of this year, the JN.1 variant of the coronavirus accounted for an overwhelming majority of Covid cases. But now, an offshoot variant called KP.2 is taking off. The variant, which made up just one percent of cases in the United States in mid-March, now makes up over a quarter. KP.2 belongs to a subset of Covid variants that scientists have cheekily nicknamed “FLiRT,” drawn from the letters in the names of their mutations. They are descendants of JN.1, and KP.2 is “very, very close” to JN.1, said Dr. David Ho, a virologist at Columbia University. But Dr. Ho has conducted early lab tests in cells that suggest that slight differences in KP.2’s spike protein might make it better at evading our immune defenses and slightly more infectious than JN.1. While cases currently don’t appear to be on the rise, researchers and physicians are closely watching whether the variant will drive a summer surge.

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