New COVID variant XEC now in half of the states. What you should know.

COVID-19 variant trackers are currently closely monitoring the rise of a new virus variant called XEC, which has been detected around the world and in half of all U.S. states.

Unlike some previous, more mutated strains that worried experts, health authorities have so far expressed no concerns about this variant.

XEC's emergence comes as COVID-19 trends remain “high” but are now largely slowing after a summer wave of infections that peaked last month. Modelers at the Centers for Disease Control and Prevention say the virus is likely to surge again in the winter, peaking in mid-January.

Here is our latest information on the new XEC variant.

From which states have XEC cases been reported?

At least 25 states have already reported at least one case with the mutations typical for the strain, according to preliminary data from the global virus database GISAID from more than 100 cases in the United States.

Labs in New Jersey have reported the most XEC infections of any state—at least 15. Only California and Virginia have reported at least 10 cases so far.

The evidence in New Jersey is based largely on samples collected as part of the CDC's testing program during customs clearance of arriving travelers at Newark Liberty International Airport.

Some of the first cases in the United States were reported by scientists at a laboratory at Virginia Tech's Fralin Biomedical Research Institute who collected samples from patients in July.

“We do not see any particular trend. We should keep an eye on the incoming samples and continue genome screening on a larger scale,” Carla Finkielstein, head of the institute's molecular diagnostics laboratory, said in an email.

Finkielstein said the majority of their samples came from hospitals throughout Southwest Virginia, although it was unclear why exactly they were tested.

“Unfortunately, we do not have demographic data on these patients. Therefore, we do not know whether the patients were in the hospital or whether their samples were taken during an emergency room visit, for example,” Finkielstein said.

Why is the XEC variant in the news?

Variant trackers first suggested calling the new variant XEC in early August, after infections were reported from labs in Europe and Virginia around the same time.

The growth of XEC in recent weeks across Germany, reported by variant trackers such as Australian consultant Mike Honey on X, has brought new attention to the variant's rise online.

However, others in the variant-tracking community are skeptical that this strain will displace other emerging strains, especially since a closely related strain called KP.3.1.1 has already achieved dominance in many countries.

KP.3.1.1 now accounts for more than half of all cases in the United States, according to CDC estimates released last Friday, and has been prevalent for several weeks.

If XEC proves dominant, it could be just the latest in a series of variants that have already resulted in relatively small changes in the threat posed by circulating variants for months.

This is in contrast to the discovery of the highly mutated Variant BA.2.86 worried health authorities this time last year because this strain had accumulated a worrying number of genetic changes compared to previous strains.

A descendant of last year's BA.2.86 strain, which was eventually named 1 Johnlater dominated the wave of infections last winter.

The “X” in XEC's name comes from the fact that the strain appears to be a “recombinant” of two other closely related parental variants called KS.1.1 and KP.3.3. Both KS.1.1 and KP.3.3 are descendants of the JN.1 strain.

Does XEC cause different symptoms or vaccine effectiveness?

“CDC is not aware of any specific symptoms associated with XEC or any other co-circulating SARS-CoV-2 strain,” an agency spokesperson said in a statement.

Americans are still advised to take a round of updated COVID-19 vaccinessaid the CDC spokesman. These vaccinations have been approved last month with an update to combat the KP.2 virus strain.

In recent weeks, the American Food and Drug Administration (FDA) has defended its selection of KP.2 as the new vaccine for this year, ignoring a recommendation from the World Health Organization and a panel of external advisers to the agency to instead target the predecessor vaccine JN.1.

The FDA said in a statement Wednesday that the agency has “high confidence” in the effectiveness of this season’s updated vaccines.

It is unclear what influence FDA officials believe XEC will have on their election. An FDA spokesman did not immediately respond to a request for comment.

“We currently assume that COVID-19 Treatments and vaccines will continue to work against all circulating variants. CDC will continue to monitor the effectiveness of treatments and vaccines against circulating variants,” the CDC spokesperson said.