FLiRT variant threatens Covid-19 wave in US

(CNN) — Covid-19 levels are near the lowest in U.S. history, but a new crop of virus variants again threatens to buck the downward trend as the country heads into summer.

KP.2 – one of the so-called FLiRT variants – has surpassed JN.1 to become the dominant coronavirus variant in the United States, according to the US Centers for Disease Control and Prevention (CDC for its acronym in English). Data through May 11 shows it accounts for more than a quarter of the country’s cases, nearly double that of JN.1. The related variant, KP.1.1, was responsible for about 7% of cases, according to the CDC.

The FLiRT variants are offshoots of the JN.1 variant – part of the wider Omicron family – which made waves this winter. The acronym in the name refers to the sites of amino acid mutations that the virus has acquired, some of which help evade the body’s immune response and others that help make it more infectious.

New covid-19 variant KP.2: here’s what you need to know

“Covid-19 variants are “accumulating mutations that do one of two things: they either cause the antibodies you made from vaccination or infection to no longer bind to the virus (we call this immune escape) or they increase “how viruses bind to cells,” said Dr. Andy Pekosh, a virologist at the Johns Hopkins Bloomberg School of Public Health.

This has become a familiar pattern in the evolution of the virus that causes Covid-19, but experts say we still don’t know enough to accurately predict where changes will occur next or how they will affect the spread of the virus through the population. .

Mutations in FLiRT variants make increased transmissibility—and a possible summer surge—a real threat. Covid-19 is following some seasonal patterns, including a rise in cases last summer, but the exact level of risk this year is unclear.

“We’ve had some options in the past that started out pretty strong and then didn’t dominate. These subvariants could gradually become dominant or account for 20% to 40% of cases and then remain there. We’ll just have to wait and see,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University. “The virus is still in control. He will tell us what he is going to do. All our crystal balls are pretty cloudy.”

Since the US public health emergency ended a year ago, Covid-19 surveillance has dropped significantly, also adding to uncertainty. But the available data are consistent. So far, wastewater surveillance shows that viral activity is very low and declining in all regions of the country, and hospitalization rates for Covid-19 remain extremely low.

“What we’ve learned from the labs is that the FLiRT variants currently appear to be as infectious as other omicron subvariants, meaning they are actually quite infectious. But they do not appear to cause more severe disease or any distinguishing symptoms.” disease in terms of clinical symptoms,” Schaffner said.

The requirement for all hospitals to report Covid-19 data to the federal government expired on May 1. But Vanderbilt Schaffner University Medical Center is part of a CDC-led surveillance network that continues to track trends based on a sample of hospitals covering about 10% of the U.S. population. The data shows hospitalization rates due to Covid-19 fell from almost 8 new hospitalizations per 100,000 people in the first week of the year to about 1 new hospitalization per 100,000 people at the end of April.

While FLiRT options pose some risk this summer, experts remain focused on what could happen in the fall.

“If I had to predict, I would say it could lead to additional cases, a slight increase, this summer. But the real question is which variant will be present when we get to the fall,” Pekosz said. “We should probably expect an increase in Covid cases in the autumn. And if we have a variant that has a lot of mutations that interfere with immunity, then the likelihood of more growth in the fall will be higher.”

According to him, northern autumn and winter pose a greater risk due to the immunity developed in the population.

“The virus now needs better conditions for transmission, and those better conditions for transmission are likely to occur in the fall when the weather gets cooler, people spend more time indoors and are more likely to be in environments where transmission of respiratory viruses occurs more frequently. more efficient.”

The study was published Wednesday in a medical journal. JAMA It’s a reminder that Covid-19 continues to wreak havoc on the US this winter, although hospitalization rates for Covid-19 were much lower than in previous years, it was still more deadly than the flu. A study of thousands of hospitalized patients found that 5.7% of patients with Covid-19 died, compared with 4.2% of patients hospitalized with the flu. In other words, the risk of death from Covid-19 is about 35% higher than from the flu.

People who received the last Covid-19 vaccine last fall may still have some protection against the latest variants; That vaccine targeted a different strain but was just as effective against JN.1, and experts say some of those benefits may extend to its FLiRT cousins. People who have recently been infected—especially since the beginning of the year when JN.1 was prominent—may also have some protection. But immunity decreases over time.

The US Food and Drug Administration’s vaccine advisory committee will meet in June to discuss recommendations for the version of the Covid-19 vaccine that will be available this fall. The meeting was delayed by about three weeks to “allow additional time to obtain surveillance data” and have “more relevant information when discussing and making recommendations,” according to a post on the federal agency’s website.

For now, experts say the risk remains relatively low.

“As with everything related to Covid, our view may change in a week or two. But right now we’re actually in a very good place, the best place we’ve been in a long, long time,” he said. .