A group of COVID-19 variants nicknamed “FLiRT” is spreading as the U.S. heads into summer.
Some of the FLiRT variants are on the rise as JN.1 – previously the dominant strain – is declining. JN.1 was the top strain circulating in the U.S. for much of the winter.
Now, KP.2 is the most prominent strain. Along with KP.1.1, the strains are descendants of JN.1. They gained the nickname FLiRT from the technical terms used for their mutations.
Here’s what to know about them:
How Prevalent Are They?
KP.2 was responsible for more than 28% of new infections during the two-week period ending on May 11, according to estimates from the Centers for Disease Control and Prevention. KP.1.1 was responsible for more than 7% of new cases.
KP.2 is also increasing globally. The World Health Organization reported that the strain accounts for nearly 10% of infections across the world, which is up from more than 6% of cases about a month prior.
Maria Van Kerkhove of WHO recently said that KP.2 is “one we’re watching.”
“The first sequences that were reported were in January this year, so it’s been circulating for some time and we expect these percentages to change,” Van Kerkhove said at a press briefing this month.
Are the FLiRT Variants Affecting COVID-19 Cases, Hospitalizations or Deaths?
Wastewater viral activity, which can help track both symptomatic and asymptomatic infections, is currently considered “minimal” on the national level, according to the CDC.
So far, KP.2 is not driving an increase in COVID-19 metrics.
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“KP.2 is the main variant in the U.S. but isn’t causing an increase in COVID-19 infections or more severe illness than other variants,” according to the CDC.
COVID-19 isn’t considered seasonal yet, so a summer wave is always a possibility. Adding to the difficulty of predictions is a decreasing amount of reliable data on COVID-19 as hospitals are no longer required to report certain COVID-19 metrics to the federal government.
And it’s not just a U.S. problem.
“With declining rates of testing and sequencing globally, it is increasingly challenging to estimate the severity impact of emerging SARS-CoV-2 variants,” WHO said in its report.
But the organization added that “there are currently no reported laboratory or epidemiological reports” that indicate increased disease severity for the variants.
Will Vaccines Work on the FLiRT Variants?
COVID-19 vaccines currently target XBB.1.5, which is no longer circulating in the U.S. However, the shots are still expected to increase protection against circulating strains.
It’s likely that federal advisers will consider the FLiRT variants when they meet in June to talk about the next COVID-19 vaccine update. The date of the meeting was originally set for this month, but it was rescheduled to “allow for additional time to obtain surveillance data and other information” so that the advisory group “will have more up-to-date information when discussing and making recommendations.”
“FDA does not anticipate that the date change will impact COVID-19 vaccine availability for the Fall,” the agency said in its announcement.
COVID-19 vaccine uptake for the latest shot was not what many hoped it would be, with less than 23% of adults rolling up their sleeves for it, according to CDC data. That’s considerably less than the uptake for the flu shot, which was 48% for adults.
