As COVID-19 activity remains high across the United States, a new hybrid variant called XEC is rapidly spreading throughout Europe and beyond. XEC has been detected in more than half of U.S. states, and experts are predicting it could become the dominant strain in the upcoming fall season. The emergence of XEC is a result of the ongoing mutation of the SARS-CoV-2 virus, which causes COVID-19, giving rise to new and highly contagious variants.
XEC is a recombinant of two previous variants, KP.3.3 and KS.1.1, which have additional mutations that may give it an advantage over other variants. XEC is a sublineage of omicron, similar to previous variants like the FLiRT strains and the dominant KP.3.1.1 variant in the U.S. Currently, XEC is spreading rapidly in Europe, North America, and Asia, with around 200 sequences detected in the U.S. in at least 26 states.
The XEC variant is highly transmissible, like other omicron variants, and is easily spread through respiratory droplets. While it has mutations in its spike protein that may contribute to its transmissibility, it is unclear whether XEC will outcompete other variants. Experts are closely monitoring the spread of XEC and its potential impact on COVID-19 transmission in the coming months, particularly as the winter respiratory virus season approaches.
There is limited information available about the symptoms of XEC, but so far, it does not appear to cause any distinctive symptoms or more severe disease than previous variants. People infected with XEC may experience common COVID-19 symptoms such as sore throat, cough, fatigue, headache, fever, and loss of taste or smell. Those in high-risk populations, such as older adults and individuals with underlying medical conditions, may be more likely to develop severe disease.
The updated COVID-19 vaccines for the 2024–2025 season are recommended for everyone aged six months and older. The vaccines target the previously dominant KP.2 variant, but early laboratory studies suggest that they will provide protection against severe disease caused by the XEC variant. Vaccine uptake is especially crucial for high-risk populations to prevent severe illness and hospitalization. Antivirals remain effective against COVID-19, particularly when taken within the first few days of symptom onset.
As fall approaches, individuals can protect themselves against COVID-19 and other respiratory viruses by staying up to date with vaccines, staying home when sick, avoiding contact with sick individuals, wearing a mask in crowded indoor spaces, improving ventilation, maintaining good hand hygiene, and practicing social distancing. Testing for COVID-19 is important if symptoms are present or there has been an exposure, and free test kits will be available for order by the end of September. Following isolation guidelines and taking antivirals as recommended can also help prevent the spread of XEC and other variants.
