What to Know About New Covid Variants, ‘FLiRT’: Symptoms, Vaccines and More

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.

“I don’t think anybody’s expecting things to change abruptly, necessarily,” said Dr. Marc Sala, co-director of the Northwestern Medicine Comprehensive Covid-19 Center in Chicago. But KP.2 will most likely “be our new norm,’” he said. Here’s what to know.

The current spread of Covid

Experts said it would take several weeks to see whether KP.2 might lead to a rise in Covid cases, and noted that we have only a limited understanding of how the virus is spreading. Since the public health emergency ended, there is less robust data available on cases, and doctors said fewer people were using Covid tests.

But what we do know is reassuring: Despite the shift in variants, data from the C.D.C. suggests there are only “minimal” levels of the virus circulating in wastewater nationally, and emergency department visits and hospitalizations fell between early March and late April.