--- title: XE Variant: What We Know So Far description: The XE variant of Omicron is spreading in the U.K., and early research suggests it's more transmissible than BA.2. Here's what to know. canonical: https://time.com/6165297/xe-variant-what-to-know/ author: Mandy Oaklander article:opinion: false article:content_tier: free article:published_time: 2022-04-08T13:21:58.000Z article:modified_time: 2026-10-14T09:34:28.334Z article:section: Health og:title: What to Know About the XE Variant og:description: The XE variant of Omicron is spreading in the U.K., and early research suggests it's more transmissible than BA.2. Here's what to know. og:url: https://time.com/6165297/xe-variant-what-to-know/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt507a6ed75b11008d/698a30b7656a3f7238bdc66d/covid-19-coronavirus-variant.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 2309 og:image:height: 1299 og:image:alt: covid-19-coronavirus-variant og:type: article twitter:card: summary_large_image twitter:title: What to Know About the XE Variant twitter:description: The XE variant of Omicron is spreading in the U.K., and early research suggests it's more transmissible than BA.2. Here's what to know. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt507a6ed75b11008d/698a30b7656a3f7238bdc66d/covid-19-coronavirus-variant.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # What to Know About the XE Variant > Sponsored content. Supplied in partnership with TIME. 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Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-health-2026q3/newsletters?i=e317527c-64e2-46d5-8142-63d3cf93dae4&cr=time-nl-health-2026q3-v1) ## Video: The Miracle Workers: The Scientists Behind The COVID-19 Vaccine [Watch (HLS stream): The Miracle Workers: The Scientists Behind The COVID-19 Vaccine](https://cdn.jwplayer.com/manifests/BTNvQC2o.m3u8) (5:16)  _Published 2021-12-13. For those of us lucky enough to live in wealthy countries with access to these top-shelf vaccines, it has made all the difference. The miracle workers behind the COVID-19 vaccines are the TIME Heroes of the Year not only because they gave the world a defense against a pathogen, but also because the manner of that astonishing achievement guards more than our health: they channeled their ambitions to the common good, talked to one another and trusted in facts._  by [Mandy Oaklander](https://time.com/author/mandy-oaklander/)  ## Mandy Oaklander Oaklander is a senior editor at TIME. Apr 8, 2022 1:21 PM UTC  by [Mandy Oaklander](https://time.com/author/mandy-oaklander/)  ## Mandy Oaklander Oaklander is a senior editor at TIME. Apr 8, 2022 1:21 PM UTC A new strain of Omicron, called XE, is spreading in the U.K., and a few cases have been identified elsewhere in the world. Here’s what we do—and don’t—know about the variant. ## What do we know about the XE variant so far? XE is a hybrid of the two now-familiar strains of Omicron: BA.1 (the original Omicron strain) and BA.2 (the more infectious related strain that’s now dominant in the U.S. and other countries). XE is known as a recombinant variant, which forms “when one SARS-CoV-2 strain picks up some genetic material from another SARS-CoV-2 strain,” explains Dr. Andrew Badley, a professor of infectious disease at the Mayo Clinic and chair of the SARS-CoV-2 COVID-19 Task Force for Mayo Clinic. That means the new recombinant variant picks up attributes associated with each strain, but not always that it turns into a more threatening version. “Recombinant variants are well described for other viruses and are not often associated with more danger,” Badley says. XE has three mutations that aren’t present in all BA.1 or BA.2 strains, according to the [U.K. Health Security Agency](https://click.newsletters.time.com/?qs=519deca956599ea1dfde5b2262e7c16af99d49ce94342dcfee9302eb902988b7d07d22acbd055b39854dfa5df61397f0c168c8ab857fdf96) (UKHSA). Experts say that since BA.1 and BA.2 are both circulating widely at the moment, it’s not surprising that a new combination strain has recently popped up. “Recombinant variants are not an unusual occurrence, particularly when there are several variants in circulation, and several have been identified over the course of the pandemic to date,” said Susan Hopkins, chief medical advisor of UKHSA, in a [statement](https://click.newsletters.time.com/?qs=519deca956599ea1a541da2f6ac1f1f829ceeff75533c409a279ef778e6c0226e5504a47fc27c1871955ea54cde1bbb55c4553a52f009355). “As with other kinds of variant\[s\], most will die off relatively quickly.” Researchers are still studying how easily the XE variant spreads. U.K. researchers have [found](https://click.newsletters.time.com/?qs=519deca956599ea1dfde5b2262e7c16af99d49ce94342dcfee9302eb902988b7d07d22acbd055b39854dfa5df61397f0c168c8ab857fdf96) that when they first analyzed XE sequences, the variant was about as transmissible as BA.2, but more recent data indicate that the variant may be 10% more transmissible. The World Health Organization’s (WHO) April 5[ report also says XE is about 10%](https://click.newsletters.time.com/?qs=519deca956599ea1b5faef833452e051d39bb77bc7865a10d900b9d2625f9602276d4b171386053907a18482b831c63e143133c441459ea6) more transmissible than BA.2, but notes that the number requires further confirmation. **Read More**: [_The First COVID-19 Breathalyzer Test Is Coming to the U.S._](https://time.com/6168141/first-covid-19-breathalyzer-test/) ## Where have cases been found? The first known case of XE was detected in the U.K. on January 19, 2022\. So far, more than 600 cases of XE have been identified there, according to a March 25 [report](https://click.newsletters.time.com/?qs=519deca956599ea1dfde5b2262e7c16af99d49ce94342dcfee9302eb902988b7d07d22acbd055b39854dfa5df61397f0c168c8ab857fdf96) from UKHSA—which is less than 1% of total sequenced cases. That’s nowhere near the rate of cases caused by BA.2, which is now the dominant form of SARS-CoV-2 both in the U.K. and [globally](https://click.newsletters.time.com/?qs=519deca956599ea1b5faef833452e051d39bb77bc7865a10d900b9d2625f9602276d4b171386053907a18482b831c63e143133c441459ea6). XE has also been found in India and Thailand. One case was [reported](https://click.newsletters.time.com/?qs=519deca956599ea192bd698933474bacc89edfd1421106adf1e1ed688208ba403d14ffc1056ef32f7453473f421e99b85a75a13322e3a29f) on April 6 in Mumbai, according to Bloomberg, and on April 4, the Center for Medical Genomics in Bangkok [reported](https://click.newsletters.time.com/?qs=519deca956599ea1cf0aea837d61bc027980c590fad5392680576e73f125925869ea2188121bf0dfb332297f0cec31ea7adc026c4b5be917) one recent case of XE. ## Should you be worried? “Like everything in the SARS-CoV-2 era, there’s no simple answer,” says Badley. “But to make it a simple answer: if you’re vaccinated and otherwise healthy, you shouldn’t worry about it. If you’re not vaccinated or have co-morbidities, there’s a cause for concern.” The good news is that there are still relatively few XE cases. “We’ve known about the existence of the XE variant since the middle of January,” Badley says. “Now, two and a half months later, we’re still seeing cases, but it hasn’t exploded.” To put that in context, “Omicron was first identified in November, and within four weeks it was all over the world. So it’s not as dominant a new strain as Omicron was,” he says. **Read More**: [_Why the Rise of Rapid Tests Makes COVID-19 Case Counts Hard to Trust_ ](https://time.com/6168809/at-home-covid-19-test-results-should-i-report/) ## What do we still not know yet? There’s not yet enough information to tell whether XE will spread more rapidly or cause more serious illness than other variants of SARS-CoV-2\. “So far there is not enough evidence to draw conclusions about transmissibility, severity, or vaccine effectiveness,” said Susan Hopkins, chief medical advisor of the UKHSA, in a[ statement](https://click.newsletters.time.com/?qs=519deca956599ea1a541da2f6ac1f1f829ceeff75533c409a279ef778e6c0226e5504a47fc27c1871955ea54cde1bbb55c4553a52f009355). However, it’s possible to infer some clues from the two strains that comprise it. “We know the vaccines work to protect against symptomatic disease for BA.1 and BA.2, and therefore we have every reason to suspect that vaccination strategies will have activity to protect against symptomatic disease caused by XE,” Badley says. Another hint is that “BA.1 and BA.2 each can escape some of the monoclonal antibody therapies,” so those drugs aren’t likely to work as well against XE either, Badley says. “We also know that the other therapies that are being used particularly in the outpatient setting—Paxlovid and molnupiravir—should, based on how they work, have continued activity against the XE strain.” UKHSA is currently monitoring XE and two other recombinant lineages—XF and XD, which are both recombinants of Delta and Omicron BA.1\. So far, UKHSA says that fewer than 40 cases of XF have been detected, all in the U.K. (though none have been seen since mid-February). XD has not been found in the U.K., but 49 cases—mostly in France—have been reported to global databases. The World Health Organization is also tracking XE, XD, and other recombinants, according to the group’s most recent [report](https://click.newsletters.time.com/?qs=519deca956599ea1b5faef833452e051d39bb77bc7865a10d900b9d2625f9602276d4b171386053907a18482b831c63e143133c441459ea6). ## Transcript Kind: captions Language: en I think vaccines are misunderstood, and maybe it's because it seems like magic. That simplicity and the mystery of it is something that ends up creating a lot of skepticism. People are fooled by the speed. Everything that we knew when it was time to design a vaccine for COVID-19, we knew for so long, but the public had just become aware of it. If this would happen two years ago, we would not be ready. Saying that it happened overnight, it took two, three decades, at least. 2021 was the year when so many praised the miracle of vaccine development. In science, there is hardly ever a simple, quick fix. But this was truly a moment of the right fix - a brand new kind of vaccine technology - at exactly the right time. I started out in math, and I moved to biology. And after medical school, I saw one of the first cases of HIV in Tennessee back in 1982. And so the first part of my career was trying to understand the immunology of vaccine-enhanced disease and trying to make vaccines safer. I got interested in science when I was 16 years old. I was hooked on the idea that you could go to work and discover something that no one else in the world knows on any given day. It seems at 16, I thought that maybe I will be a scientist. I was always working with mRNA, I mean for 30 years at least. And I never wanted to develop a vaccine. I wanted to develop it for therapy. When I first came to Penn from the NIH, pure luck hit where I met Kati Karikó over a Xerox machine. And she told me she worked on RNA, and she could help us with our vaccine. Every experiment doesn't work, every hypothesis isn't good. It was a continuous flow of negative feedback. But we saw the potential of the RNA and neither of us would give up. Although mRNA can teach our cells to fight infection, it took doctors Karikó and Weissman 16 years to figure out how to use it safely in a vaccine. First when I made this RNA, actually I did not tell Drew Weissman, my colleague, because I thought that maybe I mixed up something. So I repeated the experiment and we could see that there was no inflammation in human cells. We're both scientists. We're not baseball players who cheer when we hit a homerun. We knew that it had great potential. But what we thought about is what are we going to do with it? Meanwhile, doctors Corbett and Graham spent years unlocking the structural secrets of viruses. One of the really important problems in coronaviruses that had not been solved is really simple. What does the coronavirus really look like to the immune system? And to figure that out, you have to be able to take a really high definition picture of the proteins that are on the surface of the coronavirus. And then do some protein engineering to stabilize the structure. At that moment, you realize that you have almost what is a universal strategy for creating a vaccine for coronaviruses. A mysterious respiratory illness with similarities to SARS has healthcare workers around the world on alert. What we said to each other, all's we need is a sequence and we're ready to go. We can make a vaccine in weeks and get it into people very quickly. The fact that we made a vaccine in 10 months, and has the potential to end this pandemic, will certainly stand out. "Do it mama!" (laughter) Most scientists never get to see a product actually used. And to watch the evening news and see the relief on healthcare providers getting immunized, those were special moments. I also get emotional when I got a letter from an elderly home, and they reported that they received the vaccine. There were like 200 elderly in that home. And nobody died. On social media, when children were going back to visiting their grandparents again. Seeing people reunited in that way, it was a very surreal moment. A surreal moment, and definitely worth celebrating, if only briefly before a return to work. These scientists are now trying to apply their game-changing discoveries to other diseases. Influenza, even cancer. 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