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As the world began to recover from the Covid-19 pandemic, a new and more contagious variant, known as XEC, has emerged and is spreading swiftly across Europe. Scientists have warned that XEC could potentially become the dominant strain. It was first identified in Germany in June and has since appeared in several countries, including the UK, the US, and Denmark.
Classified as a sublineage of the Omicron variant, XEC carries mutations that may enhance its transmissibility this autumn. Despite this, vaccines are anticipated to continue offering strong protection against severe disease.
XEC as a hybrid variant
XEC is a recombinant strain derived from the earlier Omicron sub-variants KS.1.1 and KP.3.3, with KS.1.1 currently being the dominant variant in Europe. So far, approximately 500 samples containing the XEC variant have been identified across 27 countries, including Poland, Norway, Luxembourg, Ukraine, Portugal, and China, as reported by The Independent. Growth in XEC cases has been notably strong in Denmark, Germany, the UK, and the Netherlands.
The BBC noted experts as saying that XEC has a “slight transmission advantage” compared to recent variants. While vaccines are still expected to provide good protection, XEC may become the dominant strain over the upcoming winter.
Another infectious diseases expert stated that XEC is just getting started and that it could take several weeks or months before causing a significant wave of infections.
XEC might have a competitive edge due to a unique T22N mutation, along with FLuQE mutations, experts have suggested. FLuQE (KP.3) is a direct descendant of the FLiRT variant, carrying an additional amino acid mutation in the spike protein, Q493E.
In a post on X, health expert cited by BBC Eric Topol commented that XEC is likely to become the next dominant variant, with rapid spread predicted in the coming months.
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What are the symptoms of the XEC variant?
The symptoms associated with XEC are similar to those seen in previous Covid variants, including fever, sore throat, cough, loss of smell, loss of appetite, and body aches. Despite these symptoms, experts maintain that vaccines and booster shots should provide adequate protection against severe illness and hospitalisation.
The US Centers for Disease Control and Prevention (CDC) has also encouraged the public to maintain good hygiene and take steps to improve air quality as preventative measures.
Meanwhile, researchers have called for closer monitoring of the XEC variant to better understand its symptoms. Other potential symptoms might include shortness of breath, muscle aches, headaches, congestion, nausea, vomiting, and diarrhoea. Variants belonging to the FLiRT lineage, like XEC, generally cause milder symptoms compared to the original strain of Covid-19.
What are the sub-variants involved in XEC variant?
XEC is formed by the combination of KS.1.1 and KP.3.3. KS.1.1, part of the FLiRT variant, has mutations where phenylalanine (F) is replaced by leucine (L), and arginine (R) is replaced by threonine (T) in the virus’s spike protein. Meanwhile, KP.3.3, a type of FLuQE variant, carries a mutation where glutamine (Q) is converted to glutamic acid (E), enhancing its ability to bind to human cells.
Is the Covid vaccine effective against XEC?
Experts assert that vaccines and booster shots remain a crucial defence against XEC, which is part of the Omicron lineage. While XEC has a slight advantage in transmission, existing vaccines should still offer protection against severe illness. The CDC has recommended that individuals aged six months and older receive the updated 2024-2025 Covid-19 vaccine.
Doctors emphasised that current vaccines targeting Omicron variants are likely to remain effective against XEC, as the variant is not drastically different from previous strains. Therefore, vaccines should continue to protect against serious illness, hospitalisation and death.
