masked anthony fauci
© Leah Millis | ReutersDr. Anthony Fauci takes part in a meeting with U.S. President Joe Biden and Vice President Kamala Harris and other members of the White House COVID-19 Response Team on developments related to the Omicron COVID-19 variant from the State Dining Room at the White House in Washington, U.S., December 9, 2021.
Cases of Covid-19 are likely going to keep surging as the omicron variant rapidly spreads across the globe, U.S. infectious disease expert Dr. Anthony Fauci said Sunday.

"Every day it goes up and up. The last weekly average was about 150,000 and it likely will go much higher," Fauci said on ABC's "This Week."

As of Thursday, before the holiday weekend disrupted Covid trackers, the U.S. had reported more than 51 million total cases, according to the Centers for Disease Control and Prevention. The U.S. also topped 800,000 total deaths from the disease in mid-December.

Driving the surge is the omicron variant, which took over as the dominant strain a week ago.

While the strain has proven to be highly transmissible, studies are starting to indicate it is less severe in terms of hospitalizations. Still, Fauci stressed now is not the time to "get complacent."

"If you have many, many, many more people with a less level of severity, that might kind of neutralize the positive effect of having less severity when you have so many more people," Fauci said. "And we're particularly worried about those who are in that unvaccinated class. Those are the most vulnerable ones when you have a virus that is extraordinarily effective in getting to people and infecting them the way omicron is."