The good news is that in the early spring of 2024, COVID-19 cases were down, with far fewer infections and hospitalizations than were seen in the previous winter. But SARS-CoV-2, the coronavirus that causes COVID, is still mutating, raising concerns about a potential wave of infections this summer. In April, a group of new virus strains known as the FLiRT variants (based on the technical names of their two mutations) began to spread, followed in June by a variant known as LB.1.
The FLiRT strains are subvariants of Omicron, and together they account for more than 60% of COVID cases in the U.S. (up from less than 5% in March). One of them, KP.3, accounted for 33.1% of COVID infections in the United States by the end of the first week of June; KP.2 made up 20.8%, and KP.1.1 accounted for 9% of cases.
The LB.1 strain is similar to the FLiRT variants, but with an additional mutation. As summer began, it was responsible for 17.5% of COVID cases.
Meanwhile, during the same period, the Centers for Disease Control and Prevention (CDC) reported a significant COVID uptick in several states, based on spikes in emergency room visits and detections of the virus in wastewater. (Wastewater testing can help detect the spread of a COVID in a community.)
“Viruses mutate all the time, so I’m not surprised to see a new coronavirus variant taking over,” says Yale Medicine infectious diseases specialist Scott Roberts, MD. If anything, he says the new mutations are confirmation that the SARS-CoV-2 virus remains a bit of a wild card, where it’s always difficult to predict what it will do next. “And I’m guessing it will continue to mutate.”