Cos’è XEC, la nuova variante del Coronavirus con un sintomo insolito
La nuova variante del Sars-CoV-2 sta emergendo come una delle più trasmissibili e potrebbe diventare dominante nei prossimi mesi
19 ottobre 2024
La variante XEC del Sars-CoV-2 preoccupa la comunità scientifica. Identificata per la prima volta in Germania durante l’estate del 2024, XEC è un ricombinante delle varianti KS.1.1 e KP.3.3 e, secondo un team di scienziati giapponesi, ha tutte le caratteristiche per diventare la variante predominante nei prossimi mesi.
Le caratteristiche di XEC
Uno degli aspetti che rende XEC particolarmente preoccupante è la sua trasmissibilità, superiore rispetto alla variante attualmente dominante, KP.3.1.1. In uno studio condotto dall’Università di Tokyo, i ricercatori hanno stimato il numero di riproduzione effettiva (Re) di XEC, ovvero il numero medio di nuovi casi che una persona infetta può generare. In Paesi come gli Stati Uniti, questo valore è risultato essere 1,13 volte maggiore rispetto a KP.3.1.1, suggerendo che XEC potrebbe presto soppiantare quest’ultima.
Mutazioni e immunoevasività
XEC presenta due ulteriori mutazioni nella proteina Spike, elemento chiave del virus per infettare le cellule umane. Queste mutazioni sembrano conferire al virus una maggiore infettività e una capacità di evasione immunitaria superiore a quella delle varianti precedenti. Gli esperimenti condotti su pseudovirus hanno mostrato che XEC è più resistente agli anticorpi generati da infezioni precedenti con altre varianti, in particolare KP.3.3 e JN.1. Questo potrebbe spiegare perché XEC riesce a diffondersi così rapidamente nonostante l’immunità acquisita da vaccini e infezioni passate.
Un quadro clinico simile, ma con un sintomo insolito
Dal punto di vista clinico, XEC sembra causare sintomi simili a quelli delle varianti Omicron: febbre, mal di gola, dolori muscolari e affaticamento. Tuttavia, si sta osservando un sintomo insolito che sembra essere più frequente nei pazienti infettati da XEC: la perdita dell’appetito, spesso accompagnata da diarrea e malessere generale. Questo sintomo, raramente segnalato con le precedenti varianti, sta attirando l’attenzione dei medici, soprattutto nei Paesi dove XEC è più diffusa, come Regno Unito, Stati Uniti e Francia.
La sfida per il futuro
Nonostante XEC non sembri causare una malattia più grave rispetto alle varianti precedenti, la sua elevata trasmissibilità rappresenta una sfida significativa, soprattutto con l’avvicinarsi dell’inverno e la concomitante circolazione di altri virus respiratori. Le autorità sanitarie prevedono un incremento dei casi, e si raccomanda la vaccinazione con i vaccini aggiornati, che offrono una buona protezione contro XEC.
The New XEC COVID Variant: 5 Things to Know
Health officials are keeping a close eye on the latest strain of the coronavirus
Published September 18, 2024
COVID-19’s summer surge is starting to cool off, the latest national data shows, but public health experts urge people not to let their guard down.
Cases and hospitalizations remain elevated, particularly among older adults and younger children, a Sept. 13 report from the Centers for Disease Control and Prevention (CDC) shows. Plus, COVID activity historically spikes in the fall and winter months when more people are indoors.
There’s also a new coronavirus variant that public health officials and virologists are keeping a close eye on. The strain, known as XEC, has been detected in several countries, including the U.S., where a handful of cases have been reported.
“[XEC] is starting to really show evidence of being the most rapidly increasing variant that’s causing COVID right now,” says Andrew Pekosz, a professor in the department of molecular microbiology and immunology at Johns Hopkins Bloomberg School of Public Health.
It “appears to be the most likely one to get legs next,” Eric Topol, M.D., founder and director of the Scripps Research Translational Institute, wrote on the social media platform X.
Here’s what you need to know about XEC, including how to amp up your protection against the COVID variant.
1. XEC is a hybrid variant
Researchers refer to the XEC variant, which is in the omicron family, as a recombinant virus — a hybrid of two other variants.
“I think that’s another reason why people are interested in following [XEC] right now, because [recombinant] variants oftentimes have very unpredictable results, because they’re basically resulting from two different variants sort of coming together and exchanging their genes,” Pekosz says.
XEC is a mix of KP.3.3 — an offshoot of KP.3, one of the FLiRT variants that drove the summer surge — and KS.1.1.
2. New vaccines should be a good match
Though XEC has drifted from the variants that newly updated vaccines target (KP.2 for Moderna and Pfizer-BioNTech’s vaccines, and JN.1 for Novavax’s shot), it shares similarities, so this year’s vaccines should be “a very good match” against the new variant, Pekosz says.
“From a vaccine perspective, this is one that should be recognized by the immune response induced by vaccination,” he explains. “[People] can go out and get their vaccine, and it’ll work against this variant, as well as many of the ones that are circulating right now.”
Getting vaccinated against COVID is especially important for older adults, who are at higher risk of becoming seriously sick from a coronavirus infection. This year’s updated vaccines are available in pharmacies and clinics throughout the U.S. Doctors say it’s safe to get your COVID vaccine, flu shot and RSV vaccine at the same time.
3. Cases remain low in U.S. — but that could change
Most cases of COVID-19 caused by XEC have been reported overseas, primarily in Europe. “It hasn’t gotten to the United States yet in any significant numbers,” Pekosz says — though this could change.
According to outbreak.info, a COVID-19 tracker from Scripps, 23 cases of COVID-19 caused by XEC had been identified in the U.S. as of Sept. 3. The dominant variant in the U.S. is KP3.1.1, which accounts for more than half of coronavirus infections.
Even if XEC does spread more in the U.S., “there’s no clear evidence” that it would become a dominant variant, Pekosz says. It may fold into the “swarm of variants,” like the FliRT variants and others, causing infections in the U.S. over the past several months. “This may simply become one of those variants that’s circulating together in the population,” Pekosz says.
ARTICLE CONTINUES AFTER ADVERTISEMENT
4. Symptoms don’t appear more severe
Scientists are still studying XEC, but “so far nothing jumps out in terms of having a different disease pattern with this variant yet,” Pekosz says. Meaning the symptoms you get from an infection caused by XEC are most likely going to be similar to symptoms you’d experience from another omicron variant.
According to the CDC, common symptoms of COVID-19 can include:
- Fever or chills
- Cough
- Shortness of breath or difficulty breathing
- Sore throat
- Congestion or runny nose
- New loss of taste or smell
- Fatigue
- Muscle or body aches
- Headache
- Nausea or vomiting
- Diarrhea
“But again, it’s very early. So we need a little bit more data to see if that’s happening,” Pekosz says. “Right now, the only thing that’s clear is that it seems to be the fastest increasing variant in parts of Europe, in particular.”
5. Older adults should get a plan in place
News of a new variant serves as a reminder that “this is a great time to get prepared” for the fall and winter virus season, Pekosz says. In addition to getting vaccinated, he says, now is the time to stock up on home test kits, so if you experience COVID-like symptoms, you can test yourself for the virus and, if positive, talk to your doctor about antiviral treatments to keep an infection from turning severe.
The government is relaunching its COVID home test kit program later in September. U.S. households will be able to order four free coronavirus tests shipped to their homes.
There are also home tests on the market that can tell you if you have COVID or flu, Pekosz notes. As with COVID, antiviral treatments can keep an influenza infection from turning severe, and these medications work best when started right away.