A new series of COVID variants, nicknamed the "FLiRT" variants, are being tracked by U.S. health officials, according to the Centers for Disease Control and Prevention.
The variants, identified as KP.1.1 and KP.2, collectively make up more than 32% of COVID cases in the U.S., per the CDC's most recent variant tracking data. KP.2, in particular, made up the most cases of any variant at 24.9% of cases, according to forecasting data from the week ending on April 27.
"CDC is tracking SARS-CoV-2 variants KP.2 and KP.1.1, sometimes referred to as 'FLiRT,' and working to better understand their potential impact on public health," the CDC told NBC Chicago in a statement. "Currently, KP.2 is the dominant variant in the United States, but laboratory testing data indicate low levels of SARS-CoV-2 transmission overall at this time. That means that while KP.2 is proportionally the most predominant variant, it is not causing an increase in infections as transmission of SARS-CoV-2 is low."
What are COVID FLiRT variants?
The variants are subvariants of JN.1, which rose to dominance in December 2023 and was labeled a "variant of concern," though the "FLiRT" variants have two changes in the spike protein compared to JN.1.
"The two changes in spike have been observed in earlier lineages, including XBB.1.5 lineages, which were dominant throughout 2023 and the basis for the 2023–2024 vaccine formulation," the CDC reported.
Health officials said that while there are no indicators the new strains cause more severe illness than other strains, the "CDC will continue to monitor community transmission of the virus and how vaccines perform against this strain."
Megan L. Ranney, dean of the Yale School of Public Health, told WebMD the spike protein changes are concerning.
How concerning are the new variants?
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While the emergence of the new variants has sparked concerns over a potential summer surge, health experts have stressed that COVID levels remain low compared to the start of the pandemic.
"I think it is something we're keeping our eyes on and like what's happened before, I think we are expecting to have variants every so often as COVID continues around the world and in the U.S.," Dr. Shivanjali Shankaran, an associate professor in infectious diseases at Rush University Medical Center, told NBC Chicago.
Earlier this year, COVID-19 was putting more people in the hospital than flu, but as of late-April the hospitalization rates appeared about the same, CDC data showed.
According to the CDC, KP.2 has so far not been associated with increases in test positivity or hospitalizations. But Shankaran noted that with summer gatherings and holidays near, transmission could climb.
"I think we've seen that before with multiple prior variants as well, where it's not like RSV or flu [which] only happens in the winter," she said. "So that's one thing to know about, especially as holidays come again, you know, festivals and things like that. And yes, at this point, we have a very, very small number of people who are hospitalized or ... dying from COVID, but what we need to remember is the non-serious, if you will, or non-acute side effects, such as development of long COVID, or having increased risk of developing diabetes and things like that, which are still quite very serious and still should be taken into account when you sort of move around the world."
The concerns come two months after COVID-19 guidelines were updated by the CDC, with the five-day isolation recommendation being removed. The change marked the first time the U.S. agency has loosened its COVID isolation recommendations in three years.
Vaccination levels associated with the latest version of the vaccine remain low as experts urged precautions.
"Not to say don't do anything, but just things like get the vaccine - even if the vaccine doesn't match 100%, which it hasn't for a while. We know that with prior variants even the unmatched vaccine has provided significant protection against hospitalization," Shankaran said, encouraging those who may be sick to mask where possible.
What are the symptoms?
So far, symptoms associated with the new variants appear to be similar to previous strains. If you do suspect you've contracted COVID, here are some symptoms you might experience:
- Cough
- Sore throat
- Runny nose
- Sneezing
- Fatigue
- Headache
- Muscle aches
- Altered sense of smell
Last year, a Chicago-area doctor said she's noticed shifts in the most common symptoms her patients reported as the JN.1 variant rose to dominance.
Dr. Chantel Tinfang, a family medicine physician with Sengstacke Health Center at Provident Hospital of Cook County, noted at the time that many of the cases she saw reported less of the fever, body aches and chills, and presented more with sore throat, fatigue and coughing.
"We still see some patients experiencing decreased appetite, a loss of taste or smell. So it kind of depends," she said. "One patient was just very, very tired. Like she couldn't really do much. And that's when you know ... it's different. It's not just coughing and shortness of breath. We still see that though."
She suggested consulting with your doctor if your symptoms don't begin to improve outside of the recommended isolation period.
As for timing, symptoms can last for several days, but in some cases, even longer.
"Some people who have been infected with the virus that causes COVID-19 can experience long-term effects from their infection, known as Long COVID or Post-COVID Conditions (PCC)," according to the CDC.
Such symptoms can last for weeks and possibly even years.
