Is there a new COVID variant? Omicron XE explained

A hybrid COVID variant called XE made headlines for the past week, but experts have warned people not to worry unduly – and the variant isn’t even particularly new.

XE is known as recombinant, meaning it’s essentially a hybrid of two different viruses, or variants with characteristics of both. More specifically, XE is a hybrid of the two subtypes BA.1 and BA.2 of the Omicron variant.

Recombinants occur when a person is infected with two different viruses at the same time, such as variants of COVID, causing the viruses to mix when replicating.

XE is among three recombinants recently named by researchers, the others being XD and XF. The latter two are hybrids of Omicron and Delta, which don’t seem to have spread as much as XE. XE and XF have been found in the UK, while XD has been found in other European countries.

Google Trends data shows a recent spike in search engine queries for a “new COVID variant,” but it’s worth noting that XE was first spotted on Jan. 19, so it’s been around for months.

In an epidemiological update released on March 29, the World Health Organization (WHO) found that XE may have a 10 percent growth advantage over the currently dominant BA.2 Omicron subvariant, meaning it could spread slightly faster. At this point there were at least 600 sequences.

However, Jeremy Kamil, associate professor of microbiology and immunology at Louisiana State University Health Shreveport, urged people not to worry about XE and cautioned against the media hype surrounding him.

“Overall, I find it very disappointing and unhelpful how much people play up these lines,” he said news week. “They are scientifically interesting but remain largely an oddity alongside the entire Omicron wave BA.2/BA.1/BA.1.1. These are unlikely to pose any particular or unique threat, and we shouldn’t treat them as if they are.

“XE is basically a BA.2 omicron lineage that carries a bit of BA.1 at the front end of its genome. Its peak is still BA.2. Probably over 700 cases of XE have now been sequenced. That’s not a big number.”

Andrew Freedman is Lecturer in Infectious Diseases at Cardiff University’s Center for Medical Education. He reiterated the point that XE should not be treated with undue concern at this time.

“It’s too early to assess the full significance of these recombinants, but I wouldn’t be overly concerned at this point,” he said news week. “XE has spread in the greatest numbers, particularly in the UK, but seems unlikely to elude vaccines and antibodies as these are effective in preventing serious disease from both BA.1 and BA.2.

“I think that the emergence of a new variant in the future that might be even more transmissible than Omicron and more virulent and capable of escaping the immunity conferred by current vaccines and previous infections would be much more worrying.”

None of this is to say that recombinant viruses can never be of concern. One concern with recombinants is that they could potentially – but not necessarily – combine traits from two variants to form a mixture that is more dangerous than either individually.

At the moment, however, research on these recombinants is at a relatively low level, while BA.2 causes record-breaking infections in the UK and has become by far the dominant variant in the US.

A photo shows a health worker administering a COVID test at a testing site in North Miami, Florida on January 13, 2022. The XE-COVID recombinant variant has attracted interest recently, but experts have dismissed undue concerns so far.
Joe Raedle/Getty

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