It is now estimated that more than one-third of COVID-19 cases in the U. S. have been diagnosed with COVID-19. The U. S. variants of the U. S. are coming from a fast-growing new member of an organization of so-called “FLiRT” variants, dubbed for their minor but unique tweaks to the JN. 1 strain. JN. 1, the variant that sparked last winter’s wave of infections.
The largest of these, dubbed KP. 2 by scientists, has multiplied in recent weeks to become the now-dominant new strain of COVID-19.
According to biweekly variant estimates from the Centers for Disease Control and Prevention, KP. 2 and the strain with the same FLiRT mutations, dubbed KP. 1. 1, together account for 35. 3% of projected infections this week. 7. 1% a month ago.
“This means that although KP. 2 is proportionally the peak major variant, it does not cause a buildup of infections because SARS-CoV-2 transmission is low,” a CDC spokesperson told CBS News in a statement.
The strain also does not show major worrying changes, unlike some highly mutated variants of the past that have raised alarm bells in previous years.
However, the immediate update on circulating variants has prompted the Food and Drug Administration to delay this week a key step in its process of deciding which strain to target with this fall’s COVID-19 vaccines, raising the need for more “updates. “”date”.
While federal requirements requiring hospitals to report COVID-19 knowledge to the government expired this month, the CDC says it still has reliable figures from resources like wastewater and emergency rooms to continue tracking virus activity.
Here’s the latest on what we know about COVID-19 variants in the United States.
According to the latest projections released by the CDC, about 28. 2% of national COVID-19 cases are now due to a sublineage of the virus called the KP. 2 variant.
The second major variant on the rise is a descendant of JN. 1 called JN. 1. 16. This strain hasn’t grown as fast, reaching only about 10% of cases this week.
This projection is based on genetic sequences of the virus reported basically through public fitness labs, which have declined particularly in recent weeks in parallel with the general slowdown in cases. The CDC’s other knowledge of wastewater and traveler testing still fails to distinguish KP. 2 from its parent JN. 1.
KP. 2 is a very similar descendant of last winter’s JN. 1 variant, which has been found to be not particularly severe than previous dominant variants, despite its gigantic number of mutations.
“So this is a factor that we’re monitoring. This is a factor we are monitoring. And again, let’s reiterate the need for continued surveillance of SARS-CoV-2 in people around the world, so that we can track this evolution. ” said the World Health Organization’s Maria Van Kerkhove told reporters on Wednesday.
The FLiRT moniker comes from two distinct mutations seen in several descendants of the JN. 1 variant that emerged around the world after the winter passed. Some of the largest strains recently with FLiRT mutations in the United States are KP. 2 and KP. 1. 1.
“This is to inform about the express amino acid adjustments in the spike protein F456L R346T, or from phenylalanine (F) to leucine (L) at position 456 and arginine [R] to threonine [T] at position 346. “Canadian biologist Ryan Gregory, a professor at the University of Guelph, told CBS News in an email.
Gregory coined the nickname in March and it has gained traction among variant trackers who have detected and dubbed many of the virus’s unique settings a pandemic. Although not official, those nicknames have become commonly used names for a number of variations.
FLiRT prevailed over the nickname (the “tiLT” variants) coined by Australian representative Mike Honey. FLiRT refers to a set of faster-growing JN. 1 branches that crawlers monitor, including KP. 2.
“Basically, lately almost everything is descended from BA. 2. 86. 1. 1 (JN. 1) and things are moving quickly, so it makes more sense to focus on mutations of interest rather than individual variants at this point,” Gregory wrote.
Unlike some highly mutated variants that had raised concerns about the prospective course of symptoms in recent years, the JN. 1 variant that many Americans likely already acquired over the winter is very similar to the KP. 2 strain, which has been on the rise lately. .
“Based on existing data, there is no indication that KP. 2 causes more severe illness than the strains,” a CDC spokesperson told CBS News.
KP. 2’s two unique mutations called FLiRT were also seen earlier, in the XBB. 1. 5 variants that circulated in 2023, the spokesperson said.
A draft study by Japanese scientists, published as a preprint that has not yet been peer-reviewed, found that the variant appeared to dodge antibodies more than the JN. 1 variant. This “increased immune resistance” likely explains their rise, according to the scientists.
Governments and fitness experts have generally downplayed claims that the variants cause other symptoms. Changes in a person’s immunity due to past vaccinations and infections play a role in other symptoms, rather than expressing mutations.
“Mutations occur frequently, but they only replace features of the virus,” the CDC explains.
The CDC has not made any adjustments to its existing vaccine recommendations, which were last updated in April. But the emergence of those new descendants of JN. 1 variants like KP. 2 may be the vaccine the FDA chooses for next fall. and winter.
Most Americans remain eligible to receive at least one dose of the COVID-19 vaccine to date last season, which, according to CDC data so far, was up to 51% effective compared to emergency room or urgent care visits at a time when JN. 1 was on the rise.
“CDC will continue to monitor the virus transmission network and the effectiveness of vaccines against this strain,” the KP. 2 company said.
Last month, experts at the World Health Organization said vaccine brands are producing shots directed against the JN. 1 variant for the upcoming season. A panel of FDA vaccine experts was scheduled to compare this technique for the U. S. vaccine market next week.
However, the company recently announced that it had to postpone the assembly until June in hopes of buying more time to ensure it chooses a vaccine target that is “best suited to be used for the strains that are expected to circulate. “in the country. autumn.
“The FDA, along with its public fitness partners, are closely monitoring trends in circulating SARS-CoV-2 strains. As has been the case since the emergence of COVID-19, we have recently observed adjustments in the dominant circulating strains of SARS-CoV. . -2,” an FDA spokesperson told CBS News in a statement.
Pfizer has generated information from studies on its KP. 2 vaccines, but a company spokesperson said he couldn’t last a few percents of the results. A Moderna spokesperson did not respond to a request for comment.
A Novavax spokesperson said it was aware that its fall vaccine candidate, planned for JN. 1, had “good cross-reactivity” for KP. 2. Although Novavax’s vaccine takes longer to manufacture than Pfizer and Moderna’s mRNA shots, the spokesperson said the FDA’s delay in the assembly will “impact” its ability to administer a shot this fall.
“We have manufactured JN. 1 in accordance with recommendations and are on track to deliver an updated vaccine this fall,” the Novavax spokesperson said.