New virus variants threaten a summer Covid-19 wave, but experts say the risk remains uncertain

Covid-19 levels are about the lowest they’ve ever been in the United States, but another new crop of virus variants once again threatens to disrupt the downward trend as the country heads into summer.

Covid-19 levels are about the lowest they’ve ever been in the United States, but another new crop of virus variants once again threatens to disrupt the downward trend as the country heads into summer. KP.2 — one of the so-called FLiRT variants — has overtaken JN.1 to become the dominant coronavirus variant in the United States, according to data from the US Centers for Disease Control and Prevention. Data through May 11 shows that it’s responsible for more than a quarter of cases in the country, which is nearly twice as many as JN.1. A related variant, KP.1.1, has caused about 7% of cases, CDC data shows. FLiRT variants are offshoots of the JN.1 variant — all part of the broader Omicron family — that caused this winter’s wave. The acronym in the name refers to the locations of the amino acid mutations that the virus has picked up — some in places that help it evade the body’s immune response and others that help it become more transmissible. Covid-19 variants are “accumulating mutations that do one of two things: They either cause antibodies that you’ve accumulated from vaccination or infection to no longer bind to the to the virus — we call that escape from immunity — or they increase the strength in which the viruses bind to cells,” said Dr. Andy Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health. This has become a familiar pattern in the way the virus that causes Covid-19 continues to evolve, but experts say we still don’t know enough to predict exactly where the changes will occur next or how they will affect the way the virus moves through the population. The mutations of the FLiRT variants make increased transmissibility — and a possible summer wave — a real threat. Covid-19 is settling into some seasonal patterns, which have included a summer bump in years past, but the exact level of risk for this year is unclear.