Lifestyle Health Dr. Fauci Warns COVID-19 Omicron Variant Cases 'Likely Will Go Much Higher' After Holiday Surge The nation's leading infectious disease expert warned Americans not to get "complacent" with the coronavirus — especially the unvaccinated By Abigail Adams Abigail Adams Abigail Adams is a Human Interest Writer and Reporter for PEOPLE. She has been working in journalism for seven years. People Editorial Guidelines Published on December 26, 2021 02:44PM EST Dr. Anthony Fauci is warning of a significant increase in COVID-19 cases following the holiday. The nation's leading infectious disease expert, 81, said Sunday on ABC's This Week that the United States averaged around 150,000 cases of the virus over the last seven days, and that "it likely will go much higher" in the coming weeks as the Omicron variant continues spreading rapidly. "Well, there's one thing that's for sure that we all agree upon, that it is extraordinarily contagious," Fauci told This Week co-anchor Jonathan Karl. Data from the U.K. showed that the ratio of hospitalizations to cases was lower with the Omicron variant than other strains of the COVID-19 virus, according to Fauci. Additionally, the expert said both the duration of hospital stay and the need for oxygen "was lower" among patients. But Fauci still cautioned people from getting "complacent" about the virus with so many new infections arising. Unvaccinated individuals, he said, are still among the top concerns. Times Square New Year's Eve Is Still Going Ahead But Will Be 'Scaled Back' amid COVID Surge "We're particularly worried about those who are in that unvaccinated class, that, you know, tens and tens of millions of Americans who are eligible for vaccination who have not been vaccinated," the doctor told Karl, 53. "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." ABC News/Youtube He continued, "So even though we're pleased by the evidence from multiple countries, that it looks like there is a lesser degree of severity, we've got to be careful that we don't get complacent about that … because it might still lead to a lot of hospitalizations in the United States." Former President Donald Trump reiterated his support for the COVID-19 vaccines in an interview with conservative media personality Candace Owens that aired Tuesday. At one point, Owens suggested that more people have died from COVID-19 "under Joe Biden, than under you and more people took the vaccine this year." Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. "Oh no, the vaccines work, but some people aren't the ones taking it," Trump interjected. "The ones who get very sick and go to the hospital are the ones that don't take the vaccine. But it's still their choice. And if you take the vaccine, you're protected." Fauci said Sunday that he hopes Trump's supporters will listen to what he said in the interview. "We'll take anything we can get about getting people vaccinated," he told Karl. ABC News/Youtube But the doctor admittedly "was a bit dismayed" when Trump was booed by some of his supporters after he and former FOX News host Bill O'Reilly simultaneously revealed that they had received booster shots for COVID-19. "I was stunned by that," Fauci said. "I mean, given the fact of how popular he is with that group, that they would boo him, which tells me how recalcitrant they are about being told what they should do." Donald Trump Again Offers Public Support for Vaccine: 'People Aren't Dying When They Take the Vaccine' He added, "I think that his continuing to say that people should get vaccinated and articulating that to them, in my mind, is a good thing. I hope he keeps it up." In the meantime, Fauci believes improving testing capabilities will "be very important" as the Omicron variant continues to circulate. "One of the problems is that that's not going to be totally available to everyone until we get to January, and there are still some issues now of people having trouble getting tested, but we're addressing the testing problem, and that very soon that will be corrected," Fauci said earlier in the interview. As information about the coronavirus pandemic rapidly changes, PEOPLE is committed to providing the most recent data in our coverage. Some of the information in this story may have changed after publication. For the latest on COVID-19, readers are encouraged to use online resources from the CDC, WHO and local public health departments. PEOPLE has partnered with GoFundMe to raise money for the COVID-19 Relief Fund, a GoFundMe.org fundraiser to support everything from frontline responders to families in need, as well as organizations helping communities. For more information or to donate, click here.