New COVID ‘FLiRT’ variants show virus isn’t going away

May 9, 2024

The most recently dominant variants of SARS-CoV-2, the coronavirus that causes COVID-19, are part of a group sometimes called “FLiRT” variants and serve as a reminder that the virus isn’t going away and some people continue to suffer. 

While most of the country and the federal government has put the pandemic in the rearview mirror, the virus is mutating and new variants emerging.  

So far, the variants haven’t been proven to cause any more serious illness and vaccines remain effective, but there’s no certainty about how the virus may change and what happens next. 

According to the most recent data available, weekly hospitalizations were at the lowest level since the start of the pandemic.  

But as of May 1, hospitals are no longer required to report COVID-19 hospital admissions, hospital capacity or hospital occupancy data to the federal government.  

The dominant variant KP.2 accounts for nearly 25 percent of all infections, according to the most recent data from the Centers for Disease Control and Prevention. KP.2 is a descendant of the JN.1 variant, which it recently surpassed as the dominant strain. According to CDC, JN.1 accounts for 22 percent of all infections. 

KP.2 is a member of a group of SARS-CoV-2 variants sometimes called “FLiRT” variants, named because of the technical names for their mutations, according to the Infectious Disease Society of America. Other FLiRT variants, including KP.1.1, are circulating in the U.S. but are not yet as widespread as KP.2. 

William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine, said there’s nothing substantially different about the new variants compared to past mutations of the virus. They are all subvariants of omicron, and contain spike protein mutations that make them more transmissible. 

“We’re in the omicron era, and there have been several subvariants that have become dominant. They’re highly communicable, but they don’t appear to produce more severe disease,” Schaffner said.  

The spike protein mutations mean vaccines and previously acquired immunity may not protect a person as completely as they did against earlier strains, but lab test show there’s still substantial protection against severe disease, he said. 

“We’re now treating this as one of the serious respiratory infections that are predominantly seasonal. It’s now endemic, we’re all learning how to deal with it in a routine fashion. It’s not going to go away,” Schaffner said. 

Federal health officials are planning a fall vaccination campaign, and the Food and Drug Administration this week said it is delaying an advisory committee meeting on the formulation of those shots until next month so experts can get more data on the circulating variants. 

Officials want the newest vaccine to target the dominant variant, but that can be a moving target. The real world is not a lab. By the time the shots are manufactured and distributed, there will likely be a new dominant strain; something that happens with the annual flu shot as well. 

Vaccines can protect against serious infection and hospitalization. Initial CDC data from February showed the 2023 vaccine was about 53 percent effective against symptomatic  infection. Those vaccines targeted the omicron variant XBB.1.5, which was dominant for most of 2023 but was supplanted by JN.1 shortly after the vaccines were rolled out. 

But fewer than one in four U.S. adults received the shots last fall, and there’s concern that low vaccination rates combined with mutating variants could be a recipe for a summer surge. 

The latest variant is also a reminder that some people are still suffering from “long COVID.” 

The National Institutes of Health this week said it was launching clinical trials to investigate potential treatments for long-term symptoms after COVID-19 infection, including sleep disturbances, exercise intolerance and the worsening of symptoms following physical or mental exertion.  

The new trials will enroll approximately 1,660 people across 50 study sites and add to six earlier investigations that are part of the NIH’s Researching COVID to Enhance Recovery Initiative.