What to Know About the FLiRT COVID-19 Variants

With national levels of respiratory illness declining and warmer weather on the horizon, COVID-19 may no longer be top of mind. But don’t let it slip too far, health experts warn.

“COVID is down, but it has not gone away. I would say it’s continuing to smolder out there,” says infectious disease expert William Schaffner, M.D., a professor of medicine at Vanderbilt University School of Medicine in Nashville, Tennessee.

Unlike influenza, which Schaffner says “virtually disappears” during the summer months, COVID-19 keeps circulating. In fact, federal data shows that historically, COVID-19 cases and hospitalizations spike some during the summer months.

One thing that could fuel another surge this summer: a new variant, one that is better able to escape our immune defenses from vaccines and previous infections. Right now, all eyes in the U.S. are on two variants — KP.2 and KP.1.1 — from a group known as the FLiRT variants. Together these two variants make up about one-third of infections in the U.S.   

What we know about FLiRT

No doubt we’ve seen some strange nicknames for variants throughout the COVID-19 pandemic — Arcturus, Pirola and Eris, to name a few. According to an explainer posted by the Infectious Diseases Society of America, FLiRT is an acronym for some of the variants’ spike protein mutations.

The FLiRT variants, which are still in the omicron family, appear to be highly transmissible, meaning they spread easily. However so far, they do not appear to cause more severe disease, Schaffner says.

The “slight caution” about the FLiRT variants, Schaffner says, is that from a genetic perspective, they are a little more “distant from their parents.” That means immunity from previous infections and vaccines “may not protect perfectly” against an infection with a FLiRT variant, he notes.