As the United States prepares for the cold and flu season, new COVID-19 variants are emerging, necessitating an updated approach to prevention and protection. Among the notable strains is XEC, an Omicron variant that has become the second-most prevalent in the country, accounting for over 1 in 10 cases, according to the Centers for Disease Control and Prevention (CDC).

While XEC features several spike mutations that might enhance its infectiousness, its symptoms largely mirror those of other COVID-19 strains, including fever, cough, shortness of breath, sore throat, congestion, loss of taste or smell, fatigue, muscle aches, headache, nausea, vomiting, and diarrhea.

The XEC variant has already established its presence in the U.S., detected in at least 25 states by late September. Experts like Mark Cameron, PhD, from Case Western Reserve University, suggest XEC could follow the pattern of previous variants like JN.1 in driving new infections.As the United State gears up for a potential surge of COVID-19 cases during the colder months ahead, health authorities are carefully monitoring the rise of the new coronavirus variant XEC.

Photo Credit: African CDC

According to the latest tracking charts shared by the Centers for Disease Control and Prevention (CDC), the predominant variant is currently KP.3.1.1, which was responsible for an estimated 57 percent of COVID-19 cases during the two-week period ending October 26. But XEC has risen to the No. 2 spot, causing an estimated 17 percent of cases. It accounted for fewer than 1 percent of cases a month prior.

Eric Topol, MD, director of the Scripps Research Translational Institute in La Jolla, California, recently posted on X (formerly Twitter) that the XEC variant has “the most growth advantage of any circulating [variant].”XEC is different from KP.3.1.1. because it is a “recombinant” virus, meaning it incorporates features from two other variants (in this case, KS.1.1 and KP.3.3), explainsPeter Chin-Hong, MD, a professor of medicine at the University of California in San Francisco, who specializes in infectious diseases.

XEC is a subvariant of the SARS-CoV-2 Omicronstrain, which has spawned multiple descendants since it surfaced in the U.S. in 2021. XEC first appeared in Germany in June 2024 before spreading rapidly throughout other parts of Europe.

The good news is that so far there is no evidence that XEC causes different symptoms or more severe disease than other recent strains, although a COVID infection is always a concern for certain people, including those who are older or immunocompromised.

Photo Credit: CNN

In early December, XEC was responsible for an estimated 45% of COVID infections in the U.S., making it the most common strain here (it rose from seventh place at the end of September), according to a Centers for Disease Control and Prevention (CDC) estimate at the time. It was closely followed by the KP3.1.1 strain, which accounted for 24% of infections.

The 2024–2025 COVID-19 vaccine was updated to better protect you against the COVID-19 variants circulating now. The U.S. Food and Drug Administration looked at data on which COVID-19 variants were circulating and how widespread each variant was. The FDA used this information to recommend including JN.1 antigen, and the vaccine is expected to work well against variants that are predominant now (for example, KP.3.1.1). It is also expected to work well against the variants that are increasing and likely to be predominant in the future, such as XEC or MC.1.