New XEC COVID variant on the rise: What are its symptoms?

With the respiratory virus season approaching in the United States, some countries are concerned about whether XEC could lead to a new wave of infections in the fall and whether the new COVID-19 vaccines coming to market will protect against it.

What do we know so far about the XEC variant, what symptoms does it cause and what can we expect in the next few months?

What is the XEC COVID variant?

XEC is a recombinant of two earlier variants, KP.3.3 (a FLiRT variant) and KS.1.1, Dr. Albert Ko, an infectious disease physician and professor at the Yale School of Public Health, told TODAY.com.

“If a person is infected with two different SARS-CoV-2 variants, a process called recombination can occur. This is when parts of the genetic material from one variant are recombined with the other, which can create a new strain,” says Ko.

The XEC variant is a sublineage of omicron, just like the previous variants that have been circulating in recent months, Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center, tells TODAY.com.

These include the FLiRT strains and the KP.3.1.1 variant currently prevalent in the United States, which some scientists have dubbed “DeFLuQE.”

According to Mike Honey, an Australian data scientist who has been tracking the spread of XEC, the variant first appeared in Berlin in late June and has since spread rapidly across Europe, North America and Asia, Honey wrote in a Sept. 14 post on X.

XEC is showing the “strongest growth” in Germany and Denmark, Honey added, and is spreading rapidly in many other places as well. So far, XEC has been reported in at least 27 countries.

In the United States, at least 95 cases have been reported in 12 states so far, according to the latest data from Scripps Research's COVID-19 database Outbreak.info.

“It's definitely there, but it didn't make it into the CDC tracker because not enough cases were detected,” Ko says. XEC is not yet listed in the U.S. Centers for Disease Control and Prevention's “nowcast” estimates, which project proportions of the COVID variant in the U.S. for the past two-week period.

However, this is likely to change. According to Honey, “XEC appears to be the next challenger to the currently dominant DeFLuQE variants,” he wrote in a post on X on September 14.

Is XEC more contagious?

“(XEC), like many of the other omicron variants we've seen recently, seems to be quite contagious and spreads very easily, which is why it's gaining more and more momentum,” Schaffner says.

XEC, like other COVID variants, is transmitted from person to person through respiratory droplets produced when an infected person breathes, talks, coughs or sneezes.

“It is currently increasing rapidly and is the fastest growing variant in some European countries,” Dr. Andrew Pekosz, professor and vice chair of the Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health, told TODAY.com.

“Whenever a new variant emerges and spreads rapidly, we keep our eyes on it. … That is actually the first signal that something might be happening,” says Pekosz.

The XEC variant has at least one mutation in its spike protein, Pekosz said. This could potentially make it more contagious, but it is unclear whether XEC will displace other variants.

“It seems to behave the way many of these other omicron subvariants have behaved. So far, no alarm bells have been rung regarding XEC,” says Schaffner.

Will XEC cause a market decline in the US?

“The summer wave of 2024 was more pronounced and lasted longer than we expected. It is only now beginning to subside,” says Schaffner.

There is no COVID “season” in the U.S., and activity can continue year-round. Cases peak in the winter months during respiratory virus season, experts say, but can also spike in the spring and summer, according to the CDC.

The timing and severity of COVID-19 waves are difficult to predict, Pekosz says, but he speculates that there is a chance this winter wave will come later or not be as big as the last one in the year, because the summer wave was big enough to give some people immunity. It is unclear, however, how the next few months will unfold.

It's also too early to say whether XEC or another variant will trigger a surge in the fall or winter. “New variants with new mutations are emerging and some of them are taking hold, others are not,” Ko says.

“XEC could be the next thing to take off and create a wave, but we are not sure how big that wave could be,” Ko adds.

But we do know one thing: respiratory virus season is upon us, and viruses like SARS-CoV-2 and influenza spread more easily in winter when people spend time together indoors.

“I can predict with certainty that there will be a surge in the winter. I don't know when or how strong that surge will be, but that should have nothing to do with your decision to get vaccinated,” Schaffner adds.

What are the symptoms of XEC?

XEC is still in its early stages, meaning there is not much information about the symptoms or other clinical features, Pekosz says. So far, however, XEC does not appear to cause any particular symptoms or more severe disease courses.

“It's always the same,” Schaffner adds. The symptoms caused by XEC are similar to those of previous omicron variants. These include:

• Sore throat
• Cough
• fatigue
• Headache and limb pain
• traffic jam
• Runny nose
• Fever or chills
• shortness of breath
• Nausea or loss of appetite
• Diarrhea
• Loss of taste or smell

“You can feel miserable for several days, but this can vary from person to person and in some people the infection is completely asymptomatic,” says Schaffner.

People in high-risk groups are more likely to become seriously ill. These include people over 65, people with pre-existing conditions (such as diabetes or heart disease) and people with weakened immune systems.

“There is nothing unusual about XEC, neither in terms of the symptoms it causes, nor its virulence or its ability to cause hospitalization and death,” says Ko. So far, XEC appears to be similar to KP.2 and KP.3, he adds.

Does the COVID vaccine protect against XEC?

The updated COVID-19 vaccine for 2024-2025 is available and is recommended by the CDC for everyone six months of age and older.

The new mRNA vaccines are monovalent, meaning they target one variant – in this case the previously dominant variant KP.2, Pekosz says. “It looks like (XEC) will be more closely related to the vaccine strains, so there should be good coverage,” he adds.

“Although the vaccine is new, there are already some initial laboratory studies that suggest that it protects against severe disease caused by this variant,” Schaffner adds.

According to the CDC, COVID-19 vaccines are safe and effective in protecting people from severe illness, hospitalization, and death. This means they can still provide protection even if a person gets COVID-19 after vaccination.

The strains that the COVID vaccines will be used against are selected in the summer, about three to four months before the vaccines become available, Pekosz notes. “Although the vaccine strain does not change, the virus continues to infect people and mutate, so we never have a 100 percent match,” he adds.

However, it appears that current vaccines will provide protection if the XEC variant spreads widely in the United States this fall.

“Now (until October) is a good time to get vaccinated,” Ko says. If you have recently recovered from a COVID-19 infection, the CDC recommends waiting three months to get vaccinated, but always talk to your doctor.

It's especially important for people at higher risk of severe illness to get the updated COVID-19 vaccine, Schaffner said. These groups should get vaccinated as soon as possible because the virus is still circulating in relatively high levels across the country, as TODAY.com previously reported.

Experts fear that the low willingness to be vaccinated will put the population at even greater risk this winter. “Last year we had a rather poor acceptance rate, only 24 percent of the population (who were eligible) were actually vaccinated. So I hope we do much better this fall,” says Schaffner.

Testing and isolation guidelines

Current COVID-19 tests are likely to detect the XEC variant and other strains in circulation, experts say.

People should get tested if they have symptoms of COVID-19 or have been exposed. It's also a good idea to get tested before large events or gatherings where you'll be around people who are high risk, Schaffner says.

The CDC recommends staying home if you are sick and not returning to normal activities until you are fever-free. And Symptoms have been improving for at least 24 hours.

Antiviral drugs such as Paxlovid are still effective and recommended, especially for people at high risk for severe disease, Schaffner notes. They are most effective when taken within the first few days of symptoms onset.

How to protect yourself from XEC

As fall approaches, you can take the following steps to protect yourself from COVID-19 and other respiratory viruses:

• Stay up to date on vaccinations.
• Stay home if you are sick.
• Avoid contact with sick people.
• Wear a mask in crowded indoor spaces.
• Improve ventilation.
• Make sure you practice good hand hygiene.
• Practice social distancing.