Yale Medicine A Yale Medicine expert weighs in on the potential impact of the new strains on the spread of COVID.
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. In April, a group of new virus strains known as the FLiRT variants (based on the technical names of their two mutations) emerged.
The FLiRT strains are subvariants of Omicron. One of them, KP.2, accounted for 28.2% of COVID infections in the United States by the third week of May, making it the dominant coronavirus variant in the country; another, KP.1.1, made up 7.1% of cases.
Some experts have suggested that the new variants could cause a summer surge in COVID cases. But the Centers for Disease Control and Prevention (CDC) also reports that COVID viral activity in wastewater (water containing waste from residential, commercial, and industrial processes) in the U.S. has been dropping since January and is currently “minimal.”
“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.”
Perhaps the biggest question, Dr. Roberts says, is whether the newly mutated virus will continue to evolve before the winter, when infections and hospitalizations usually rise, and whether the FLiRT strains will be included as a component of a fall COVID vaccine.
Below, Dr. Roberts answers three questions about the FLiRT variants.