As COVID-19 activity remains high across the United States, a new hybrid variant called XEC is rapidly spreading in Europe and other parts of the world, with at least 27 U.S. states detecting the variant. Some experts believe XEC could become the dominant strain in the fall. The SARS-CoV-2 virus continues to mutate, giving rise to new, highly contagious variants like XEC. The emergence of XEC comes as the U.S. sees a slight decline in COVID-19 activity following a summer wave, though wastewater data from the CDC suggests COVID activity remains high in 34 states.
XEC is a recombinant of two previous variants, KP.3.3 and KS.1.1. This new hybrid variant is similar to its parental strains but has additional mutations that may give it an advantage over other variants. XEC is classified as a sublineage of omicron, similar to previous variants that have been circulating. The World Health Organization has classified XEC as a variant under monitoring. XEC has spread to at least 32 countries, showing strong growth in various European countries, and is predicted to potentially become dominant over existing variants.
XEC appears to be highly transmissible, similar to other omicron variants, though there is no definitive evidence that it is significantly more transmissible than existing strains. It spreads through respiratory droplets and has at least one mutation in its spike protein. However, experts are not yet alarmed by the XEC variant’s transmission rate. The timing and severity of potential fall or winter surges, driven by XEC or other variants, remains uncertain, as does the impact on infection rates due to the size of the summer wave.
Symptoms caused by XEC are similar to previous omicron variants, including sore throat, cough, headache, fatigue, and fever. XEC does not appear to cause distinctive symptoms or more severe disease than other variants. People in high-risk populations, such as the elderly or those with underlying medical conditions, are more likely to develop severe disease. XEC currently accounts for a small percentage of cases in the U.S., and it is still unclear how its prevalence may change in the coming months.
The updated COVID-19 vaccine for 2024-2025 is recommended for everyone aged six months and older and is designed to target the previously dominant KP.2 variant. Early laboratory studies suggest that the updated vaccine will protect against severe disease caused by XEC, among other variants. COVID-19 vaccines are safe and effective at preventing severe illness, hospitalization, and death. Testing and isolation guidelines recommend testing for COVID-19 symptoms or exposure and staying home when sick. Antivirals like Paxlovid remain effective, particularly for high-risk individuals.
As fall approaches, individuals can protect themselves from COVID-19 and other respiratory viruses by staying up to date with vaccines, staying home when sick, avoiding contact with sick individuals, wearing masks in crowded indoor spaces, improving ventilation, maintaining good hand hygiene, practicing social distancing, and following CDC guidelines for testing and isolation. It is crucial for individuals, especially those at higher risk of severe disease, to get vaccinated and take preventive measures as respiratory virus season approaches.
