The U.S. Centers for Disease Control and Prevention (CDC) has slashed estimates of Omicron’s prevalence in the nation, suggesting that the new variant is not infecting people at the rate it had projected.

On Tuesday, new data released by CDC has shown that while Omicron remains the dominant variant, the highly contagious Delta is still a worrisome driving force behind the current surge, according to NPR.

As of December 18, the CDC had previously reported that 73% of new cases were associated with Omicron. However, on Tuesday, the agency said it revised those figures and slashed that estimate to 23%. The CDC said while Omicron was on the rise, it was not infecting people at the rate it had projected.

Dr. Shruti Gohil, an assistant professor in the Division of Infectious Diseases at UC Irvine School of Medicine, told NPR, “There’s no way around it, it is a huge swing that makes it seem like something went really wrong, but there is always a delay in the testing information that comes in, and that’s what the public should take away.”

She said the new variant struck just as public health experts were getting their bearings on testing for the Delta strain.

“The way in which we test and the way in which we have certitude about the numbers was all in flux right at that moment,” Dr. Gohil added. “Then along comes this new variant and now here you are trying to project something when you don’t have all of the mechanisms in place.”

She explained that the CDC’s latest report “adjusts the numbers and better reflects what was happening around the country at the time.”

The latest report shows that 59% of all infections in the nation were caused by Omicron as of December 25, while Delta accounted for 41% of cases during the same period. Considering the CDC’s margin of error on the collected data, the number of Delta infections could be even higher, which could be around 58%.

Dr. Gohil said, “The implication is that we have a lot of Delta going on and that requires a lot more attention. People are thinking, ‘Oh, well, Omicron’s not that bad.’ But it’s actually still too early to really know even that. Besides, Delta is the beast that you should be worried about.”

Before the emergence of Omicron, Delta was the most contagious variant of the virus, with studies suggesting that it may be more likely to result in hospitalization in unvaccinated people.

Dr. Gohil explained that the latest report is also forcing hospitals to recalibrate because treating Omicron or Delta requires different medications and antibody treatments. She said, “The bottom line is don’t take your masks off just yet and get vaccinated, vaccinated, vaccinated, vaccinated, and boosted.”