The ‘Kraken’ COVID variant has competition at the top—‘Cerberus’ is running neck and neck in the U.S.

(Credit: Beata Zawrzel/NurPhoto via Getty Images)

The U.S. Centers for Disease Control and Prevention dropped stunning data Friday that put a damper on the rise of new COVID variant XBB.1.5—the so-called Kraken—and left it jockeying for dominance with competitor BQ.1.1, known as Cerberus. Experts maintain that Kraken variant will continue its rise, though, and that Friday’s data is a statistical blip.

Last week, the CDC had projected that XBB.1.5 comprised about 40% of cases in the U.S. With a doubling time of about nine days, according to the CDC’s European counterpart, many expected it to achieve dominance in the U.S. when the CDC updated its weekly COVID forecast Friday. But the figures shifted. On Friday, the CDC retroactively adjusted figures, blunting Kraken’s quick rise. It’s now projected that the new variant comprised about 18% of cases this week—and will comprise about 28% of cases in the coming week.

The CDC did not immediately respond to Fortune’s request for the reason behind the change. But a large batch of COVID viral sequences from outside the northeast U.S. has recently been uploaded, changing the picture, variant tracker Dr. Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark., told Fortune. 

XBB.1.5 is responsible for the lion’s share of cases in the Northeast, but BQ variants still dominate the rest of the country, according to CDC data. Given that the Northeast in general, and New York in particular, have been frontrunning nationwide COVID trends since the beginning of the pandemic, Rajnarayanan expects XBB.1.5 to still outcompete BQ.1.1 in the U.S., eventually.

Northeast region dominance of XBB.1.5 unchanged, 5 of the 8 regions still in single digits pic.twitter.com/013DOVZXwF

— Eric Topol (@EricTopol) January 6, 2023

Sequence count by US State

Large share of sequences from outside NE States with specimen collection dates in the last 15 days. The proportion of BQ.1*/BQ.1.1* >> XBB.1.5 outside NE states. XBB.1.5 is expected to outcompete all other circulating lineages soon.

2/n pic.twitter.com/aiQnJvT3PJ

— Raj Rajnarayanan (@RajlabN) January 6, 2023

So does Dr. Eric Topol, a professor of molecular medicine at Scripps Research and founder and director of the Scripps Research Translational Institute. The tempered forecast leaves “more runway before this variant achieves dominance cross country,” he said in a Friday tweet.

New @CDCgov #SARSCoV2 variant report
Corrects/ lowers XBB.1.5 proportion of new cases from ~40% (last week) to 28% nationally now, leaving more runway before this variant achieves dominance cross country. No other variant showing growthhttps://t.co/jjl2AnOYb5 pic.twitter.com/SGHJmQ12NH

— Eric Topol (@EricTopol) January 6, 2023

XBB.1.5 has the potential to cause a global wave like Omicron BA.5 did this summer—but not as massive as the global Omicron BA.1 wave last winter, which was the largest the world has seen yet, Rajnarayanan said. A recent study by Dr. Yunlong Cao of Peking University in Beijing and other Chinese researchers made the same assertion, saying that XBB.1.5 is “highly likely” to eventually engulf the globe.

Last fall, top U.S. infectious disease expert Dr. Anthony Fauci labeled the BQ family of COVID variants “pretty troublesome” as they continued their upward ascent in the U.S., beating back a wave of BA.5 that swelled this past summer.

XBB and BQ variants are among the most immune-evasive seen to date, experts say. And as many predicted, they’re now duking it out for U.S. dominance.