Nearly 1 in 10 new COVID-19 cases in the U.S. are from the BA.2.86 variant, according to estimates by the Centers for Disease Control and Prevention on Monday. This is almost three times higher than the agency's previous estimate of the prevalence of this highly mutated variant two weeks ago.
The latest figures indicate that BA.2.86's prevalence has increased significantly, leading the CDC to list it as a separate variant in their estimates for the first time. Scientists had initially reported the discovery of this highly mutated strain during the summer.
Until now, health officials had attributed the majority of new COVID-19 cases to the XBB variant and its closely related descendants, including the HV.1 and EG.5 variants, which are currently the most common nationwide.
The CDC's estimates for BA.2.86's prevalence come with a wide margin of error. The agency states that as little as 4.8% or as much as 15.2% of circulating SARS-CoV-2 could be attributed to the BA.2.86 variant.
According to the latest estimate, the percentage of new cases of the BA.2.86 variant of COVID-19 has nearly tripled since November 11. On that date, only 3.0% of new cases were estimated to be BA.2.86, but as of November 25, the estimate has risen to 8.8%. The CDC, which typically publishes variant estimates every other Friday, delayed last week's release until after the Thanksgiving holiday weekend.
The World Health Organization has also classified BA.2.86 and its descendants as a "variant of interest" due to the increase in cases caused by this strain.
Early data suggests that BA.2.86 does not result in worse or different symptoms compared to previous strains, as stated by the World Health Organization in its November 21 risk evaluation.
The CDC has recently observed an uptick in indicators tracking the spread of COVID-19 across the United States as winter approaches.
After weeks of mostly stable or declining trends, the CDC reported that emergency department visits for COVID-19 have started to increase nationwide. This trend is seen in virtually all regions of the country, with even slight increases being observed. The Midwestern region, which includes Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin, is experiencing some of the highest increases, approaching levels not seen since early January.
Is the JN.1 variant to blame?
Since August, BA.2.86's broad array of mutations did not appear to be enough for the strain to gain a foothold over XBB and its descendants. Months of the highly mutated variant's spread only resulted in a small share of cases throughout the world.
But scientists in recent months have been studying a steep increase in a BA.2.86 descendant called JN.1, which quickly rose to become the fastest-growing subvariant worldwide.
Many cases have been reported in Europe, which has seen increasing cases from BA.2.86 and its descendants. The strain's prevalence is as high as 22.7% in Spain.
Data from recent weeks tallied from
A spokesperson for the agency did not immediately respond to a request for comment.
Last month, the CDC said it expected COVID-19 tests and treatment would remain effective against JN.1, which is closely related to BA.2.86 aside from a single change to its spike protein that early research suggests is enabling it to spread faster.
This season's vaccines are also expected to work against JN.1 similar to what was estimated for its BA.2.86 parent, the agency said.
