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As of October 4, the XEC variant of COVID-19 has been detected in at least 33 countries and 29 states across the U.S. This new strain is raising concerns due to its increased transmissibility and unique characteristics. However, experts say the latest COVID-19 booster shot, though less effective against XEC compared to previous strains, still provides some level of protection.
The Centers for Disease Control and Prevention (CDC) estimates that XEC accounted for about 6.0 percent of new COVID-19 cases in the past two weeks. A recent study supports the claim that while the new booster neutralizes the strain, it does so with slightly diminished efficacy. The unique behavior of XEC can be attributed to its being a recombinant variant, meaning it combines genetic material from two previous subvariants instead of undergoing typical mutation patterns.
Scott Roberts, the associate medical director of Infection Prevention at Yale New Haven Health, highlighted the implications of this type of variant. “Recombination, in theory, is a bit scarier [compared to typical mutations] because you could have a complete reassortment of the viral genome where all of a sudden it picks up 30 mutations from a very distantly related virus and can now fully bypass our immune defenses and lead to a big surge,” Roberts explained.
XEC is a combination of two Omicron subvariants, KS.1.1 and KP.3.3, which have been circulating since 2022. Roberts reassured that the threat from XEC, while serious, is not as concerning as previous variant shifts like the transition from Delta to Omicron in 2021. “The good news is that this is a recombinant combination of two Omicron subvariants,” he said, adding that it is not “a new Greek letter or anything where it’s an out-of-left-field thing we should be worried about.”
While XEC spreads more rapidly, it has not been shown to cause more severe illness than previous Omicron variants. Still, recombinant variants can be particularly dangerous for immunocompromised individuals, who may be unable to clear the virus from their systems, leading to accelerated mutation rates.
Albert Ko, a professor of public health and epidemiology, urged individuals living with high-risk people to get vaccinated. “We’re living with parents and grandparents who may have comorbidities, which includes just being old. That’s a good reason why we should get vaccinated,” Ko said. He stressed the importance of herd immunity and noted that while the vaccine may not perfectly match XEC, it still offers vital protection against severe illness.
Experts agree that vaccination remains critical, as it helps protect against severe outcomes, even with XEC’s recombinant nature. Roberts emphasized, “The vaccine will work, but not as well as [with] current circulating variants.”
