Fauci warns omicron cases 'likely will go much higher'

As the "extraordinarily contagious" omicron variant surges across the United States, Dr. Anthony Fauci warned that COVID-19 cases will likely continue to climb.

"Every day it goes up and up. The last weekly average was about 150,000 and it likely will go much higher," Fauci told ABC "This Week" co-anchor Jonathan Karl.

While Fauci said studies show omicron is less severe in terms of hospitalizations, he stressed, "we don't want to get complacent" because "when you have such a high volume of new infections, it might override a real diminution in severity."

"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," he explained. "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."

On Tuesday, President Joe Biden announced a plan to distribute 500 million free at-home rapid tests to Americans beginning in January. The tests will be delivered by mail to Americans who request them. A website to request the tests will launch in January, according to the administration.

But the omicron surge created a massive rush for tests as Americans prepared to see relatives for the holidays, and they instead faced empty pharmacy shelves and massive test lines.

On Wednesday, ABC News' "World News Tonight" anchor David Muir, asked Biden if that was a failure.

"I don't think it's a failure," Biden replied in the exclusive interview. "I think it's -- you could argue that we should have known a year ago, six months ago, two months ago, a month ago."

"I wish I had thought about ordering" 500 million at-home tests "two months ago," he told Muir.

Biden added "nothing's been good enough" when it comes to the availability of at-home tests.

When Karl asked about the comments, Fauci admitted to "This Week" he is frustrated with at-home test availability and said "we've obviously got to do better."

"The beginning of the year, there were essentially no rapid point of care home tests available. Now, there are over nine of them and more coming," Fauci said. "The production of them has been rapidly upscaled, and yet because of the demand that we have, which in some respects, Jon, is good, that we have a high demand because we should be using testing much more extensively than we have."

"But the situation where you have such a high demand, a conflation of events, omicron stirring people to get appropriately concerned and wanting to get tested as well as the fact of the run on tests during the holiday season -- we've obviously got to do better," he continued. "I think things will improve greatly as we get into January. But that doesn't help us today and tomorrow."

Karl also asked about the FDA last week granting emergency authorization to both Pfizer and Merck’s antiviral pills to treat COVID-19.

"Is this really the breakthrough that you've been waiting for?” Karl questioned.

"That's part of the comprehensive approach to this outbreak. Vaccines and boosters, masks and now very importantly, a highly effective therapy is really going to make a major, major difference,” Fauci replied. “We've just got to make sure that there's the production of enough of that product that we can get it widely used for those who need it as quickly as possible."

"I assume that will be a top priority going forward, right? I mean, possibly including Defense [Production] Act … and the like?" Karl pressed.

"Absolutely, Jon, absolutely,” Fauci said. "We've got to get that product into the mouths of those who need it."

Only 61.7% of the U.S. population is fully vaccinated against COVID-19, according to CDC data. Many Americans remain against COVID-19 vaccines over one year into their use.

The omicron surge doesn't appear to sway unvaccinated Americans. According to a Kaiser Family Foundation poll this week, just 12% percent of unvaccinated Americans polled said the variant makes them more likely to get a vaccine.

Former President Donald Trump showed his support for vaccinations, who has spread conspiracy theories about vaccines and didn't get vaccinated publicly, showed his support for COVID-19 vaccines in a Wednesday interview with The Daily Wire’s Candace Owens, saying, "The results of the vaccine are very good. ... People aren’t dying when they take the vaccine."

Karl asked Fauci whether Trump’s supporters might listen to that message.

“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,” Fauci responded.

Fauci also said he was surprised when Trump was booed by some of his supporters in Texas last weekend after the former president revealed he'd gotten his booster shot.

"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."