A new Omicron spawn fueling a surge of cases in India—considered the most transmissible COVID variant yet—has reached reportable levels in the U.S., the Centers for Disease Control and Prevention said Friday.
And it’s coming in hot. XBB.1.16, dubbed “Arcturus” by variant trackers, is estimated to be behind 7% of COVID cases in the country this week, according to the CDC’s Nowcast, a viral forecast released each Friday by the national public health agency. The variant doesn’t look to cause more severe disease, according to a COVID situation report released Thursday by the World Health Organization.
XBB.1.16 is a recombinant of two descendants of so-called stealth Omicron BA.2. A preprint study updated Sunday from scientists at the University of Tokyo suggests that the variant spreads about 1.17 to 1.27 times as efficiently as relatives XBB.1 and XBB.1.5, the latter of which still dominates U.S. cases.
XBB.1.16’s increased ability to outpace other variants suggests that it “will spread worldwide in the near future,” researchers wrote, adding that the variant is “robustly resistant” to antibodies from a variety of COVID variants, including “stealth Omicron” BA.2 and BA.5, which surged globally last summer.
That means it could cause cases to rise again, even in areas that have recently seen increased COVID infections—and especially if those infections stemmed from either BA.2, BA.5, or their descendants.