Is There a New COVID Variant? Omicron XE Explained

A hybrid COVID variant known as XE has sparked headlines over the past week, but experts have warned people not to get unduly concerned—and the variant isn't even particularly new.

XE is known as a recombinant, meaning it is essentially a mixture of two different viruses or variants with characteristics of both. Specifically, XE is a mixture of the two Omicron variant sub-types BA.1 and BA.2.

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

XE is among three recombinants to have been named by researchers recently, with the others being XD and XF. The latter two are mixtures of Omicron and Delta which do not appear to have spread as much as XE. XE and XF have been found in the U.K., while XD has been found in other countries in Europe.

Google Trends data shows a recent increase in search engine queries for a "new COVID variant", but it's worth noting that XE was first detected on January 19, so it has been around for months.

In an epidemiological update published on March 29, the World Health Organization (WHO) noted that XE may have a growth advantage of 10 percent over the currently dominant BA.2 Omicron sub-variant, meaning it could spread slightly faster. There had been at least 600 sequences by that time.

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

"Altogether I find it very disappointing and unhelpful how much people are hyping these variants," he told Newsweek. "They are scientifically interesting but remain largely a curiosity next to the overall BA.2 / BA.1 / BA.1.1 Omicron wave. These are not at all likely to pose a special or unique threat and we should not treat them as if they do.

"XE is basically a BA.2 Omicron lineage carrying a piece of BA.1 at the front end of its genome. Its spike is still BA.2. By now there are probably over 700 cases of XE that have been sequenced so far. That is still not a huge number."

Andrew Freedman is a reader in infectious diseases at Cardiff University's Centre for Medical Education. He echoed the point that XE should not be treated with undue concern at the moment.

"It is too early to assess the full significance of these recombinants but I would not be unduly concerned at this stage," he told Newsweek. "XE is the one that has spread in greatest numbers particularly in the U.K., but it seems unlikely that it will be able to evade vaccines and antibodies, given that these are effective in preventing severe disease due to both BA.1 and BA.2.

"I think of much greater concern would be the appearance in the future of a new variant that might be even more transmissible than Omicron and more virulent, as well as being able to evade the immunity conferred by the current vaccines and previous infections."

None of this is to say that recombinant viruses cannot ever be worrying. One concern about recombinants is that they could potentially—but not necessarily—combine features of two variants to make a mixture that is more dangerous than both of them individually.

For the moment, however, research in these relatively low-level recombinants is ongoing while BA.2 drives record-breaking infections in the U.K. and has become the dominant variant in the U.S. by far.

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